Polyamonds

A polyamond is a counterpart to a polyomino where the polygon used for tiling the plane is an equilateral triangle rather than a square.

Like polyominoes, but unlike polyhexes, polyamonds have a three dimensional counterparts. These are formed by aggregating tetrahedra.

The word polyamond is a back-formation from the word diamond motivated by the fact that this word is often used to describe the shape of a pair of equilateral triangles placed base to base.