(The Aztecs and Mayans built their pyramids with tiered steps and a flat top.) The ancient Egyptians probably chose that distinctive form for their pharaohs' tombs because of their solar religion ...

There are five platonic solids, the tetrahedron, cube, octahedron ... Image caption, A pyramid is made up of a polygonal base face and triangular faces that meet at a point called the apex.

You've probably seen them on your ice cube trays ... are often triangular because ice crystals tend to meet at 60-degree angles. An ice spike that takes the shape of an inverted pyramid is ...

Cubes and pyramids are examples of polyhedra ... a polyhedron that can be obtained by attaching a triangular pyramid to each face of another triangular pyramid. The researchers generated ...