There are no other shapes that have only four flat faces except for a tetrahedron, although the faces thatmake up the tetrahedron can be triangles of various shapes and need not be all identical.
A tetrahedron
a tetrahedron is a shape with 4 triangular faces, 6 sides and 4 vertices [corners]
A tetrahedron.
Tetrahedron
Tetrahedron
A tetrahedron.
A tetrahedron.
A tetrahedron is the smallest possible polyhedron: a closed 3-d shape with polygonal faces. It has 4 triangular faces, 4 vertices and 6 edges.
A tetrahedron
A tetrahedron.
A tetrahedron
A regular tetrahedron (triangular pyramid).