triakis tetrahedron (truncated tetrahedron)

In geometry, a triakis tetrahedron (or kistetrahedron^[1]) is an Archimedean dual solid, or a Catalan solid. Its dual is the truncated tetrahedron.

It can be seen as a tetrahedron with triangular pyramids added to each face; that is, it is the Kleetope of the tetrahedron. It is very similar to the net for the 5-cell, as the net for a tetrahedron is a triangle with other triangles added to each edge, the net for the 5-cell a tetrahedron with pyramids attached to each face. This interpretation is expressed in the name.

The length of the shorter edges is _3/5 that of the longer edges^[2]. If the triakis tetrahedron has shorter edge length 1, it has area _5/3√11 and volume _25/36√2.

https://en.wikipedia.org/wiki/Triakis_tetrahedron