Small trisoctachoron

The small trisoctachoron, or sto, is a nonconvex uniform polychoron that consists of 8 tetrahedra, 8 octahemioctahedra, and 8 truncated tetrahedra. One tetrahedron, three octahemioctahedra, and three truncated tetrahedra join at each vertex.

It also has 8 tetrahedra as pseudofacets.

It is one of two members of the regiment of the rectified tesseract to have only half the symmetry, the other is the great trisoctachoron.

Vertex coordinates
Its vertices are the same as those of its regiment colonel, the rectified tesseract.