diff --git a/df_caverns/underworld.lua b/df_caverns/underworld.lua
index 59e26f8..6415255 100644
--- a/df_caverns/underworld.lua
+++ b/df_caverns/underworld.lua
@@ -443,7 +443,7 @@ minetest.register_on_generated(function(minp, maxp, seed)
 			local index2d = mapgen_helper.index2d(emin, emax, x, z)
 			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
-			local floor_height =  math.floor(abs_cave * floor_mult + median + floor_displace + wave)
+			local floor_height =  math.floor(abs_cave * floor_mult + median + floor_displace + wave)-1
 			local ceiling_height =  math.floor(abs_cave * ceiling_mult + median + ceiling_displace + wave)
 			if floor_height < ceiling_height then
 				local zone = math.abs(nvals_zone[index2d])
diff --git a/df_underworld_items/puzzle_seal.lua b/df_underworld_items/puzzle_seal.lua
index 1cdadd8..514e139 100644
--- a/df_underworld_items/puzzle_seal.lua
+++ b/df_underworld_items/puzzle_seal.lua
@@ -149,7 +149,7 @@ local show_key = function(pos, index)
 		maxexptime = 3,
 		minsize = 1,
 		maxsize = 1,
-		texture = "dfcaverns_glow_amethyst.png",
+		texture = "dfcaverns_puzzle_particle.png",
 		glow = 8,
 	})
 end
@@ -388,6 +388,7 @@ local capstone_def = {
 	paramtype = "light",
 	paramtype2 = "facedir",
 	groups = slade_groups,
+	light_source = 8,
 	sounds = default.node_sound_stone_defaults({ footstep = { name = "bedrock2_step", gain = 1 } }),
 	is_ground_content = false,
 	on_blast = function() end,
diff --git a/df_underworld_items/textures/dfcaverns_puzzle_particle.png b/df_underworld_items/textures/dfcaverns_puzzle_particle.png
new file mode 100644
index 0000000..8fcb641
Binary files /dev/null and b/df_underworld_items/textures/dfcaverns_puzzle_particle.png differ