diff --git a/maidroid_tool/egg_writer.lua b/maidroid_tool/egg_writer.lua
index 4a755bc..f0e8638 100644
--- a/maidroid_tool/egg_writer.lua
+++ b/maidroid_tool/egg_writer.lua
@@ -85,19 +85,129 @@ do -- register egg writer
 		},
 	}
 
+	local function get_nearest_egg_entity(pos)
+		local all_objects = minetest.get_objects_inside_radius(pos, 1.0)
+		for _, object in ipairs(all_objects) do
+			if object:get_luaentity().name == "maidroid_tool:egg_entity" then
+				return object:get_luaentity()
+			end
+		end
+		return nil
+	end
+
+	local function on_deactivate(pos)
+		local egg_entity = get_nearest_egg_entity(pos)
+		egg_entity:stop_move()
+	end
+
+	local function on_activate(pos)
+		local egg_entity = get_nearest_egg_entity(pos)
+		egg_entity:start_move()
+	end
+
+	local function on_metadata_inventory_put_to_main(pos)
+		local center_position = {
+			x = pos.x, y = pos.y + 0.25, z = pos.z
+		}
+		local egg_entity = minetest.add_entity(center_position, "maidroid_tool:egg_entity")
+		local lua_entity = egg_entity:get_luaentity()
+		lua_entity:initialize(center_position)
+	end
+
+	local function on_metadata_inventory_take_from_main(pos)
+		local egg_entity = get_nearest_egg_entity(pos)
+		egg_entity.object:remove()
+	end
+
 	maidroid_tool.register_writer("maidroid_tool:egg_writer", {
-		description     = "maidroid tool : egg writer",
-		formspec        = formspec,
-		tiles           = tiles,
-		node_box        = node_box,
-		selection_box   = selection_box,
-		duration        = 40,
-		empty_itemname  = "maidroid:empty_egg",
-		dye_item_map    = dye_item_map,
+		description                           = "maidroid tool : egg writer",
+		formspec                              = formspec,
+		tiles                                 = tiles,
+		node_box                              = node_box,
+		selection_box                         = selection_box,
+		duration                              = 40,
+		on_activate                           = on_activate,
+		on_deactivate                         = on_deactivate,
+		empty_itemname                        = "maidroid:empty_egg",
+		dye_item_map                          = dye_item_map,
+		on_metadata_inventory_put_to_main     = on_metadata_inventory_put_to_main,
+		on_metadata_inventory_take_from_main  = on_metadata_inventory_take_from_main,
 	})
 
 end -- register egg writer
 
 do -- register a definition of an egg entity
+	local function on_activate(self, staticdata)
+		self.object:set_properties{textures={"maidroid:empty_egg"}}
 
-end
+		if staticdata ~= "" then
+			local data = minetest.deserialize(staticdata)
+			self.is_moving = data["is_moving"]
+
+			if self.is_moving then
+				self:start_move()
+			end
+		end
+	end
+
+	local function start_move(self)
+		self.object:set_properties{automatic_rotate = 1}
+		is_moving = true
+	end
+
+	local function stop_move(self)
+		self.object:set_properties{automatic_rotate = 0}
+		is_moving = false
+	end
+
+	local function get_staticdata(self)
+		local data = {
+			["is_moving"] = self.is_moving,
+			["center_position"] = self.center_position,
+		}
+		return minetest.serialize(data)
+	end
+
+	local function on_step(self, dtime)
+		if self.is_moving then
+
+		end
+		-- move up and down.
+		if self.angle >= 360 then
+			self.angle = 0
+		else
+			self.angle = self.angle + 3
+		end
+		local current_pos = self.object:getpos()
+		self.object:setpos(
+			vector.add(current_pos, {
+				x = 0,
+				y = math.sin(self.angle * math.pi / 180.0) * 0.0025,
+				z = 0
+			})
+		)
+	end
+
+	local function initialize(self, pos)
+		self.center_position = pos
+		local init_pos = vector.add(pos, {x = 0.15, y = 0, z = 0})
+		self.object:setpos(init_pos)
+	end
+
+	minetest.register_entity("maidroid_tool:egg_entity", {
+		hp_max           = 1,
+		visual           = "wielditem",
+		visual_size      = {x = 0.2, y = 0.2},
+		collisionbox     = {0, 0, 0, 0, 0, 0},
+		physical         = false,
+		on_activate      = on_activate,
+		start_move       = start_move,
+		stop_move        = stop_move,
+		get_staticdata   = get_staticdata,
+		on_step          = on_step,
+		initialize       = initialize,
+		center_position  = nil,
+		is_moving        = false,
+		angle            = 0,
+	})
+end -- register egg entity