The truncated 5-cell, truncated pentatope or truncated 4-simplex is bounded by 10 cells: 5 tetrahedra, and 5 truncated tetrahedra. Each vertex is surrounded by 3 truncated tetrahedra and one tetrahedron; the vertex figure is an elongated tetrahedron.
Read more about Truncated 5-cell: Bitruncated 5-cell, Related Regular Skew Polyhedron