usually, polyhedra are named by the number of faces they have. the first polyhedra are the tetrahedron, which is made of four triangles, pentahedron (five faces, can look like a four-sided pyramid), hexahedron (six faces, a cube if it is regular), heptahedron (seven faces) and octahedron (eight faces). prisms, pyramids and other shapes can also be named according to how many faces they have.