PuzzleSign

 Description:

Sign that shows that a player that the a puzzle can be entered

Dimesion:
 * Tree Signpost with an the Danish Tourist Attraction Sign
 * http://www.picturesof.net/_images_300/Danish_Tourist_Attraction_Road_Sign_Royalty_Free_Clipart_Picture_090629-185259-466048.jpg

Function:
 * Tree Signpost is placed at entrance
 * Blocks at the entrance disappear (e.g. grass)
 * Tree signpost is biome depended for city, glaizer and jungle, so 3 signpost are needed (e.g. Snow or ice on signpost)