18-4 gyrochoron

The 18-4 gyrochoron, also known as rocky 18, is a convex isochoric polychoron and member of the gyrochoron family with 18 identical cells.

Each cell of this polychoron has mirror symmetry, with 2 octagons, 2 hexagons, 5 tetragons, and 2 triangles for faces.