Anthill Art fills ant colonies with molten aluminum, creating massive, intricate castings of the architecture of the ants' nests. They're for sale on Ebay (surprisingly cheap, too), and they're spectacular.
I make casts of ant colonies using molten aluminum to fill the tunnels and chambers of the nest. The result is an amazing sculpture showing the intricate detail of the nest architecture. The cast is then mounted for display on a wood base. Each display has a stainless steel plaque mounted on it with information on the cast and a unique cast number. These make perfect displays for a home or as an educational piece for teachers and professors to display in a science classroom or laboratory.
(Thanks, Fipi Lele!)