Simple examples of Goldberg polyhedra include the dodecahedron and truncated icosahedron. Its dual polyhedron is the rhombic dodecahedron. The figures below show some stellations of the regular octahedron, dodecahedron, and icosahedron. However, neither the regular icosahedron nor the regular dodecahedron are amongst them. The remaining 12 octahedral cells project onto the 12 rhombic faces of the rhombic dodecahedron. A twelve-faced polyhedron is a dodecahedron. The remaining 12 octahedral cells project onto the faces of the rhombic dodecahedron. The graph of the rhombic dodecahedron is nonhamiltonian. The first stellation, often simply called the stellated rhombic dodecahedron, is well known. The rhombic dodecahedron, seen as a limiting case of the pyritohedron, has octahedral symmetry. The set of vertices can be considered as the edges of a rhombic dodecahedron. A rectified regular dodecahedron forms an icosidodecahedron. The elongated dodecahedron and trapezo-rhombic dodecahedron variations, along with the rhombic dodecahedra, are space-filling. The sides of a regular dodecahedron are regular pentagons, which for Pythagoreans symbolized health. It stands 60 metres high with a dodecahedron tank atop a pentagonal pillar.