diff --git a/df_caverns/underworld.lua b/df_caverns/underworld.lua
index c0708c4..6f8d3fe 100644
--- a/df_caverns/underworld.lua
+++ b/df_caverns/underworld.lua
@@ -224,11 +224,8 @@ local get_pit = function(pos)
 	local radius = variance_multiplier * (radius_pit_max - 15) + 15
 	local variance = radius_pit_variance/2 + radius_pit_variance*variance_multiplier/2
 	local depth = math.random(plasma_depth_min, plasma_depth_max)
-	
-	local shaft_seed = math.random()
-	local shaft_location = corner_xz
 	math.randomseed(next_seed)
-	return {location = location, radius = radius, variance = variance, depth = depth}, {seed = shaft_seed, location = shaft_location}
+	return {location = location, radius = radius, variance = variance, depth = depth}
 end
 
 local perlin_pit = {
@@ -248,10 +245,9 @@ minetest.register_chatcommand("find_pit", {
 	decription = "find a nearby glowing pit",
 	func = function(name, param)
 		local player = minetest.get_player_by_name(name)
-		local pit, shaft = get_pit(player:get_pos())
+		local pit = get_pit(player:get_pos())
 		if pit then
 			minetest.chat_send_player(name, "Pit location: x=" .. math.floor(pit.location.x) .. " z=" .. math.floor(pit.location.z))
-			minetest.chat_send_player(name, "Shaft location: x=" .. math.floor(shaft.location.x) .. " z=" .. math.floor(shaft.location.z))
 		end
 	end,
 })
@@ -273,7 +269,7 @@ minetest.register_on_generated(function(minp, maxp, seed)
 	local nvals_wave = mapgen_helper.perlin2d("df_caverns:underworld_wave", emin, emax, perlin_wave) --cave noise for structure
 	local nvals_zone = mapgen_helper.perlin2d("df_caverns:underworld_zone", emin, emax, perlin_zone) --building zones
 	
-	local pit, shaft = get_pit(minp)
+	local pit = get_pit(minp)
 	--minetest.chat_send_all(minetest.pos_to_string(pit.location))
 
 	local buildings = get_buildings(emin, emax, nvals_zone)
@@ -300,7 +296,7 @@ minetest.register_on_generated(function(minp, maxp, seed)
 				then
 					-- there's a pit nearby
 					if pit_uninitialized then
-						nvals_pit, area_pit = mapgen_helper.perlin3d("df_cavern:perlin_cave", minp, maxp, perlin_pit) -- determine which areas are spongey with warrens
+						nvals_pit, area_pit = mapgen_helper.perlin3d("df_cavern:perlin_cave", minp, maxp, perlin_pit)
 						pit_uninitialized = false
 					end
 					local pit_value = nvals_pit[area_pit:index(x,y,z)] * pit.variance
@@ -401,7 +397,7 @@ minetest.register_on_generated(function(minp, maxp, seed)
 	
 	-- puzzle seal
 	local puzzle_seal = nil	
-	if pit_uninitialized and minp.x == shaft.location.x and minp.z == shaft.location.z then
+	if pit_uninitialized and math.random() < 0.025 then
 		local index2d = mapgen_helper.index2d(emin, emax, minp.x + 3, minp.z + 3)
 		local abs_cave = math.abs(nvals_cave[index2d]) -- range is from 0 to approximately 2, with 0 being connected and 2s being islands
 		local wave = nvals_wave[index2d] * wave_mult
@@ -429,7 +425,9 @@ minetest.register_on_generated(function(minp, maxp, seed)
 	
 	if puzzle_seal ~= nil then
 		minetest.place_schematic({x=puzzle_seal.x-3, y=puzzle_seal.y, z=puzzle_seal.z-3}, df_underworld_items.seal_temple_schem, 0, {}, true)
-		minetest.set_node(puzzle_seal, {name="df_underworld_items:puzzle_seal"})
+		local node_name = minetest.get_node(puzzle_seal).name
+		local node_def = minetest.registered_nodes[node_name]
+		node_def.on_construct(puzzle_seal)
 	end
 	
 	if bones_loot_path then
diff --git a/df_underworld_items/puzzle_seal.lua b/df_underworld_items/puzzle_seal.lua
index 62615d5..c14e558 100644
--- a/df_underworld_items/puzzle_seal.lua
+++ b/df_underworld_items/puzzle_seal.lua
@@ -4,23 +4,148 @@ local S, NS = dofile(MP.."/intllib.lua")
 
 local invulnerable = df_underworld_items.config.invulnerable_slade and not minetest.settings:get_bool("creative_mode")
 
-local get_formspec = function(pos, completion)
-	completion = completion or 0.5
+-- Ensures that the node is functioning correctly
+local ensure_meta = function(pos)
+    local meta = minetest.get_meta(pos)
+	if not meta:contains("key") then
+		local inv = meta:get_inventory()
+		inv:set_size("main", 8)
+		local next_seed = math.random() * 2^21
+		math.randomseed(pos.x + pos.z^16)
+		-- Key is consistent with location
+		local key = {math.random(0,7), math.random(0,7), math.random(0,7), math.random(0,7), math.random(0,7), math.random(0,7),math.random(0,7), math.random(0,7)}
+		math.randomseed(next_seed)
+		meta:set_string("key", minetest.serialize(key))
+		meta:mark_as_private("key")
+	end
+	
+	local timer = minetest.get_node_timer(pos)
+	if not timer:is_started() then
+		timer:start(4)
+	end
+end
+
+local colour_groups = {
+	"color_black",	-- 0
+	"color_red",	-- 1
+	"color_orange",	-- 2
+	"color_yellow",	-- 3
+	"color_green",	-- 4
+	"color_blue",	-- 5
+	"color_violet",	-- 6
+	"color_white"}	-- 7
+
+local test_key = function(pos)
+    local meta = minetest.get_meta(pos)
+	if not meta:contains("key") then
+		return false
+	end
+		
+	local keystring = meta:get_string("key")
+	local key = minetest.deserialize(keystring)
+	local inv = meta:get_inventory()
+	
+	for offset = 0, 7 do
+		local valid
+		for i = 0, 7 do
+			valid = true
+			local keyval = (i + offset) % 8 + 1
+			local key_group = colour_groups[key[keyval]+1]
+			local item = inv:get_stack("main", i+1)
+			if minetest.get_item_group(item:get_name(), key_group) == 0 then
+				valid = false
+				break
+			end
+		end
+		if valid then
+			meta:set_int("unlocked", 1)
+			return true
+		end
+	end
+	meta:set_int("unlocked", 0)
+	return false
+end
+
+local formspec_prefix = "df_underworld_items_puzzle_seal:"
+local get_formspec = function(pos, unlocked)
 	local formspec = 
-		"size[10,10]"
-		.."list[nodemeta:"..pos.x..","..pos.y..","..pos.z..";main;1,1;3,3;]"
-		.."container[5,0.5]"
-		.."box[0,0;1,5;#0A0000]box[0.1,0.1;0.8,4.8;#000000]box[0.1," .. 0.1 + 4.8*completion ..";0.8,".. 4.8*completion ..";#FFCC22]"
+		"size[8,8]"
+		.."container[2.25,0]"
+		.."list[nodemeta:"..pos.x..","..pos.y..","..pos.z..";main;0.25,0.25;1,1;0]"
+		.."list[nodemeta:"..pos.x..","..pos.y..","..pos.z..";main;1.25,0;1,1;1]"
+		.."list[nodemeta:"..pos.x..","..pos.y..","..pos.z..";main;2.25,0.25;1,1;2]"
+		.."list[nodemeta:"..pos.x..","..pos.y..","..pos.z..";main;2.5,1.25;1,1;3]"
+		.."list[nodemeta:"..pos.x..","..pos.y..","..pos.z..";main;2.25,2.25;1,1;4]"
+		.."list[nodemeta:"..pos.x..","..pos.y..","..pos.z..";main;1.25,2.5;1,1;5]"
+		.."list[nodemeta:"..pos.x..","..pos.y..","..pos.z..";main;0.25,2.25;1,1;6]"
+		.."list[nodemeta:"..pos.x..","..pos.y..","..pos.z..";main;0,1.25;1,1;7]"
+	if unlocked then
+		formspec = formspec .. "image_button[1.25,1.25;1,1;dfcaverns_seal.png;open;"..S("Turn").."]"
+	else
+		formspec = formspec .. "image[1.25,1.25;1,1;dfcaverns_seal.png]"
+	end
+	
+	formspec = formspec
 		.."container_end[]"
-		.."container[1,5.75]list[current_player;main;0,0;8,1;]listring[]"
+--		.."container[5,0.5]"
+--		.."box[0,0;1,5;#0A0000]box[0.1,0.1;0.8,4.8;#000000]box[0.1," .. 0.1 + 4.8*completion ..";0.8,".. 4.8*completion ..";#FFCC22]"
+--		.."container_end[]"
+		.."container[0,4]list[current_player;main;0,0;8,1;]listring[]"
 		.."list[current_player;main;0,1.25;8,3;8]container_end[]"
 	return formspec
 end
+local refresh_formspec = function(pos, player)
+	local player_name = player:get_player_name()
+	local unlocked = test_key(pos)
+	local formspec = get_formspec(pos, unlocked)
+	minetest.show_formspec(player_name, formspec_prefix..minetest.pos_to_string(pos), formspec)
+end
 
-local ensure_inventory = function(pos)
+local show_key = function(pos, index)
+    minetest.sound_play("dfcaverns_seal_key", {
+        pos = pos,
+        gain = 0.125,
+        max_hear_distance = 16,
+    })
     local meta = minetest.get_meta(pos)
-	local inv = meta:get_inventory()
-	inv:set_size("main", 3*3)
+	local keystring = meta:get_string("key")
+	local key = minetest.deserialize(keystring)
+	--minetest.chat_send_all(keystring)
+	local minpos = vector.add(pos, {x=-1, y=1, z=-1})
+	local maxpos = vector.add(pos, {x=1, y=3, z=1})
+	minetest.add_particlespawner({
+		amount = key[index+1],
+		time = 0.5,
+		minpos = minpos,
+		maxpos = maxpos,
+		minvel = {x=-0.25, y=0, z=-0.25},
+		maxvel = {x=0.25, y=0.25, z=0.25},
+		minacc = {x=0, y=0, z=0},
+		maxacc = {x=0, y=0, z=0},
+		minexptime = 3,
+		maxexptime = 3,
+		minsize = 1,
+		maxsize = 1,
+		texture = "dfcaverns_glow_amethyst.png",
+		glow = 8,
+	})
+end
+
+local show_unlocked = function(pos)
+	-- Plays globally. This is deliberate.
+	minetest.sound_play("dfcaverns_seal_unlocked", {
+        gain = 1.0,
+        pitch = 1.0,
+    })
+	minetest.add_particle({
+		pos = pos,
+		velocity = {x=0, y=1, z=0},
+		expirationtime = 30,
+		size = 20,
+		texture = "dfcaverns_seal.png^[invert:rgb^[brighten",
+		glow = 15,
+--		vertical = true,
+	})
 end
 
 local puzzle_seal_def = {
@@ -32,7 +157,7 @@ local puzzle_seal_def = {
 	tiles = {"dfcaverns_slade_block.png", "dfcaverns_slade_block.png^dfcaverns_seal.png", "dfcaverns_slade_block.png"},
 	paramtype = "light",
 	paramtype2 = "facedir",
-	light_source = 12,
+	light_source = 8,
 	groups = {stone=1, level=3, slade=1, pit_plasma_resistant=1, mese_radiation_shield=1, not_in_creative_inventory=1},
 	sounds = default.node_sound_stone_defaults({ footstep = { name = "bedrock2_step", gain = 1 } }),
 		selection_box = {
@@ -47,25 +172,107 @@ local puzzle_seal_def = {
 	on_blast = function() end,
 	on_rotate = function() return false end,
 	on_construct = function(pos)
-	    ensure_inventory(pos)
+	    ensure_meta(pos)
 	end,
 	on_rightclick = function(pos, node, clicker, itemstack, pointed_thing)
-		minetest.get_node_timer(pos):start(1)
-		--ensure_inventory(pos) -- needed because mapgen doesn't call on_construct
-		--local player_name = clicker:get_player_name()
-		--minetest.show_formspec(player_name, "df_underworld_items_puzzle_seal:"..minetest.pos_to_string(pos)..":"..player_name, get_formspec(pos))
+		ensure_meta(pos)
+		refresh_formspec(pos, clicker)
+	end,
+	on_timer = function(pos, elapsed)	
+		local meta = minetest.get_meta(pos)
+		if meta:get_int("unlocked") > 0 then
+			show_unlocked(pos)
+		else
+			local index = meta:get_int("key_index")
+			show_key(pos, index)
+			meta:set_int("key_index", (index+1) % 8)
+		end
+		minetest.get_node_timer(pos):start(4)
+	end,
+	on_metadata_inventory_move = function(pos, from_list, from_index, to_list, to_index, count, player)
+		refresh_formspec(pos, player)
+	end,
+	on_metadata_inventory_put = function(pos, listname, index, stack, player)
+		refresh_formspec(pos, player)
+	end,
+	on_metadata_inventory_take = function(pos, listname, index, stack, player)
+		refresh_formspec(pos, player)
+	end,
+}
+
+if invulnerable then
+	puzzle_seal_def.groups.immortal = 1
+else
+	puzzle_seal_def.groups.cracky = 3
+end
+
+minetest.register_node("df_underworld_items:puzzle_seal", puzzle_seal_def)
+
+--------------------------------------------------------------------------------
+-- Once the seal is opened, it turns into this and digs its way down through the slade.
+
+local digging_seal_def = {
+	description = S("Slade Digging Seal"),
+	_doc_items_longdesc = nil,
+	_doc_items_usagehelp = nil,
+	drawtype = "mesh",
+	mesh = "underworld_seal.obj",
+	tiles = {"dfcaverns_pit_plasma_static.png", "dfcaverns_pit_plasma_static.png^dfcaverns_seal.png", "dfcaverns_pit_plasma_static.png"},
+	paramtype = "light",
+	paramtype2 = "facedir",
+	light_source = 15,
+	groups = {immortal=1, stone=1, level=3, slade=1, pit_plasma_resistant=1, mese_radiation_shield=1, not_in_creative_inventory=1},
+	sounds = default.node_sound_stone_defaults({ footstep = { name = "bedrock2_step", gain = 1 } }),
+		selection_box = {
+		type = "fixed",
+		fixed = {-0.625, -0.625, -0.625, 0.625, 0.625, 0.625},
+	},
+	collision_box = {
+		type = "fixed",
+		fixed = {-0.625, -0.625, -0.625, 0.625, 0.625, 0.625},
+	},
+	is_ground_content = false,
+	on_blast = function() end,
+	on_rotate = function() return false end,
+	on_construct = function(pos)
+		minetest.get_node_timer(pos):start(0)
 	end,
-	
 	on_timer = function(pos, elapsed)
 		local node = minetest.get_node(pos)
 		local below_node = minetest.get_node({x=pos.x, y=pos.y-1, z=pos.z})
 		if below_node.name == "ignore" then
-			minetest.get_node_timer(pos):start(1)
+			minetest.get_node_timer(pos):start(4)
 			return
 		end
+
+		minetest.sound_play("dfcaverns_massive_digging", {
+			pos = pos,
+			gain = 1.0,
+			max_hear_distance = 32,
+		})
+		
+		local minpos = vector.add(pos, {x=0, y=-1, z=0})
+		minetest.add_particlespawner({
+			amount = 100,
+			time = 4,
+			minpos = minpos,
+			maxpos = minpos,
+			minvel = {x=-5, y=0, z=-5},
+			maxvel = {x=5, y=20, z=5},
+			minacc = {x=0, y=-10, z=0},
+			maxacc = {x=0, y=-10, z=0},
+			minexptime = 5,
+			maxexptime = 15,
+			minsize = 1,
+			maxsize = 5,
+			texture = "dfcaverns_glowpit_particle.png",
+			collisiondetection = true,
+			collision_removal = true,
+			glow = 15,
+		})
 		
 		if minetest.get_item_group(below_node.name, "slade") == 0 then
-			minetest.set_node(pos, {name="air"})
+			minetest.set_node(pos, {name="default:lava_source"})
 			return
 		end
 		
@@ -88,23 +295,28 @@ local puzzle_seal_def = {
 		minetest.set_node(pos, {name="air"})
 		local newpos = {x=pos.x, y=pos.y-2, z=pos.z}
 		minetest.set_node(newpos, node)
-		minetest.get_node_timer(newpos):start(1)		
-	end,
-	on_metadata_inventory_move = function(pos, from_list, from_index, to_list, to_index, count, player)
-	end,
-	on_metadata_inventory_put = function(pos, listname, index, stack, player)
-	end,
-	on_metadata_inventory_take = function(pos, listname, index, stack, player)
+		minetest.get_node_timer(newpos):start(4)
 	end,
 }
 
-if invulnerable then
-	puzzle_seal_def.groups.immortal = 1
-else
-	puzzle_seal_def.groups.cracky = 3
-end
+minetest.register_node("df_underworld_items:digging_seal", digging_seal_def)
 
-minetest.register_node("df_underworld_items:puzzle_seal", puzzle_seal_def)
+local prefix_len = string.len(formspec_prefix)
+minetest.register_on_player_receive_fields(function(player, formname, fields)
+	if formname:sub(1,prefix_len) ~= formspec_prefix or not fields.open then
+		return
+	end
+	local pos_string = formname:sub(prefix_len+1)	
+	local pos = minetest.string_to_pos(pos_string)
+	if test_key(pos) then
+		minetest.set_node(pos, {name="df_underworld_items:digging_seal", param2 = math.random(1,4)-1})
+		minetest.get_node_timer(pos):start(4)
+		minetest.close_formspec(player:get_player_name(), formname)
+	end
+end)
+
+-----------------------------------------------------------------------------------------
+-- Schematics
 
 local n1 = { name = "df_underworld_items:slade_block" }
 local n5 = { name = "default:meselamp" }
diff --git a/df_underworld_items/sounds/dfcaverns_massive_digging.1.ogg b/df_underworld_items/sounds/dfcaverns_massive_digging.1.ogg
new file mode 100644
index 0000000..0f73c50
Binary files /dev/null and b/df_underworld_items/sounds/dfcaverns_massive_digging.1.ogg differ
diff --git a/df_underworld_items/sounds/dfcaverns_massive_digging.2.ogg b/df_underworld_items/sounds/dfcaverns_massive_digging.2.ogg
new file mode 100644
index 0000000..7352741
Binary files /dev/null and b/df_underworld_items/sounds/dfcaverns_massive_digging.2.ogg differ
diff --git a/df_underworld_items/sounds/dfcaverns_massive_digging.3.ogg b/df_underworld_items/sounds/dfcaverns_massive_digging.3.ogg
new file mode 100644
index 0000000..ec7ebe9
Binary files /dev/null and b/df_underworld_items/sounds/dfcaverns_massive_digging.3.ogg differ
diff --git a/df_underworld_items/sounds/dfcaverns_seal_key.ogg b/df_underworld_items/sounds/dfcaverns_seal_key.ogg
new file mode 100644
index 0000000..ecbcab5
Binary files /dev/null and b/df_underworld_items/sounds/dfcaverns_seal_key.ogg differ
diff --git a/df_underworld_items/sounds/dfcaverns_seal_unlocked.ogg b/df_underworld_items/sounds/dfcaverns_seal_unlocked.ogg
new file mode 100644
index 0000000..34b82a5
Binary files /dev/null and b/df_underworld_items/sounds/dfcaverns_seal_unlocked.ogg differ
diff --git a/df_underworld_items/sounds/license.txt b/df_underworld_items/sounds/license.txt
index 195505b..862bd6a 100644
--- a/df_underworld_items/sounds/license.txt
+++ b/df_underworld_items/sounds/license.txt
@@ -9,4 +9,10 @@ dfcaverns_grinding_stone.3.ogg - from https://freesound.org/people/FreqMan/sound
 dfcaverns_arcing.1.ogg - from https://freesound.org/people/unfa/sounds/264827/ by unfa under Creative Commons BY 3.0
 dfcaverns_arcing.2.ogg - from https://freesound.org/people/unfa/sounds/264827/ by unfa under Creative Commons BY 3.0
 dfcaverns_arcing.3.ogg - from https://freesound.org/people/unfa/sounds/264827/ by unfa under Creative Commons BY 3.0
-dfcaverns_arcing.4.ogg - from https://freesound.org/people/unfa/sounds/264827/ by unfa under Creative Commons BY 3.0
\ No newline at end of file
+dfcaverns_arcing.4.ogg - from https://freesound.org/people/unfa/sounds/264827/ by unfa under Creative Commons BY 3.0
+
+dfcaverns_seal_unlocked.ogg - from https://freesound.org/people/juskiddink/sounds/74920/ by juskiddink under Creative Commons BY 3.0
+dfcaverns_seal_key.ogg - from https://freesound.org/people/Veiler/sounds/209894/ by Veiler under the Creative Commons 0 public domain license
+dfcaverns_massive_digging.1.ogg - from https://freesound.org/people/OGsoundFX/sounds/423120/ by OGsoundFX under Creative Commons BY 3.0
+dfcaverns_massive_digging.2.ogg - from https://freesound.org/people/OGsoundFX/sounds/423120/ by OGsoundFX under Creative Commons BY 3.0
+dfcaverns_massive_digging.3.ogg - from https://freesound.org/people/OGsoundFX/sounds/423120/ by OGsoundFX under Creative Commons BY 3.0
\ No newline at end of file