The pentagonal rotunda is a convex polyhedron with regular polygonal faces. These faces comprise ten equilateral triangles, six regular pentagons, and one regular decagon, making a total of seventeen. The pentagonal rotunda is an example of Johnson solid, enumerated as the sixth Johnson solid . It is another example of an elementary polyhedron because by slicing it with a plane, the resulting smaller convex polyhedra do not have regular faces.