Print out a picture (providing clues to some mystery), glue it to a dollar store puzzle (children's puzzle for a quick one) then turn it over and cut it up with an exacto knife. It may have been a mosaic or bas-relief sculpture from the wall in the room
I did this once, and the picture I used was a picture depicting a ritual of sorts.
Explaining that these were all pieces of some clay pottery that was apparently smashed.
once they got several pieces together they realized the ritual that needed to be done and found the spot in the dungeon to do it, which in turn ended up being not a smart thing to do...
