Snub disphenoid

The snub disphenoid, or snadow, is one of the 92 Johnson solids (J84). It consists of 4+8 triangles as faces.

It can be constructed from a tetrahedron, seen as a digonal antiprism or disphenoid, by expanding the two halves outward and inserting a set of 8 triangles in between the halves.

Related polyhedra
The snub disphenoid can be considered to be the digonal case in the family of snub antiprisms. The snub triangular antiprism is the regular icosahedron, and the snub square antiprism is another Johnson solid. No other members of this family can be made to have all regular faces.