Heptahedron

3D Model

A convex heptahedron with rotational symmetry of order 3.

It has 12 edges, 9 of which have right dihedral angles, and the remaining three have dihedral angles of 135°. These three edges are all orthogonal to each other.

Joining one of these to its mirror image on one of the quadrilateral faces, and adding a prism, gives the decahedron.