Small retrohecatonicosihexacosihecatonicosachoron

The small retrohecatonicosihexacosihecatonicosachoron, or sirhixhi, is a nonconvex uniform polychoron that consists of 120 truncated dodecahedra, 600 truncated tetrahedra, and 120 icosidodecatruncated icosidodecahedra. Two truncated dodecahedra, two truncated tetrahedra, and four icosidodecatruncated icosidodecahedra join at each vertex.

Vertex coordinates
The vertices are the same as those of the regiment colonel, the small sphenoverted hexacosidishecatonicosachoron.