It contains ten tetrahedra, five cubes, an icosahedron and a dodecahedron. The icosahedron and the dodecahedron are Platonic solids with 30 edges. 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. In geometry, an icosahedron ( or ) is a polyhedron with 20 faces. The rhombic icosahedron is a zonohedron made up of 20 congruent rhombs. The 5-cube can be projected down to 3 dimensions with a rhombic icosahedron envelope. Its convex hull is the regular convex icosahedron. The vertices of a regular icosahedron are those of three mutually orthogonal golden rectangles. The convex hull of two opposite edges of a regular icosahedron forms a golden rectangle. These systems have hexagonal cell regions created on the surface of a spherical icosahedron. The skeleton of the icosahedron (the vertices and edges) forms a graph. It shares the same vertex arrangement as the convex regular icosahedron. It shares the same vertex arrangement as the regular convex icosahedron. Another common assembly is a truncated icosahedron.