Heptahedron 七面体
A heptahedron (plural: heptahedra) is a polyhedron having seven sides, or faces.
A heptahedron can take a surprising number of different basic forms, or topologies. Probably most familiar are the hexagonal pyramid and the pentagonal prism. Also notable is the tetrahemihexahedron, whose seven equilateral triangle faces form a rudimentary projective plane. No heptahedra are regular.