Octahedron with Concave Faces (CFW 226)

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This polyhedron is like a regular octahedron whose each face was replaced with a triangular pyramid pointing inwards. The three faces other than the base are equilateral right triangles, so these pyramids fully fill the inside of the octahedron, resulting in a skeleton consisting just of three intersecting squares. Just like a normal octahedron, this shape is difficult to photograph since only a few faces are ever visible at the same time.