Polyhedron formed by joining two congruent regular
pyramids base-to-base.
The regular
octahedron is the only regular bipyramid.
All the faces of a bipyramid are
triangles, since the solid is made up of two pyramids.
Bipyramids are classified according to the polygon that forms the base of each joined pyramid.
The bipyramid below has a
hexagonal or 6-sided base.
