The simple octahedron is inscribed with the center of every tetrahedron. In the image on the right, the yellow face of octahedron is exposed; the central triangle in the three other faces are part of the octahedron. The other four faces are internal, facing an abutting tetrahedron.
There are six half-sized octahedrons in each corner of the octahedron and a tetrahedron in each face. There are many two-dimensional internal plates. Outlined in colored tape, the white, red, yellow and blue hexagons are outlined. There are also plates of squares and triangles.