Great Dodecahedron
What is the great dodecahedron?
The great dodecahedron is one of the 4 concave regular polyhedra. It has the following properties:
Vertex figure: (5.5.5.5.5)/2
Faces: 12
Edges: 30
Vertices: 12
Characteristic: -6
More information can be found here: https://en.wikipedia.org/wiki/Great_dodecahedron