Reptiles are known for polyominoes, polyiamonds, polyaboloes, and other polyforms.
Few polyforms of any kind form reptiles. A bireptile is a figure of which copies can be joined to form two joined, equally enlarged copies of the original figure.
Any figure with a reptiling trivially has a bireptiling, but not every figure with a bireptiling has a reptiling. That is, bireptiles are more common than reptiles.
Below I show minimal known bireptilings for various polyiamonds.
Last revised 2015-12-10.