Elongated bipyramid

In geometry, the elongated bipyramids are an infinite set of polyhedra, constructed by elongating an bipyramid.
There are three elongated bipyramids that are Johnson solids:

Higher forms can be constructed with isosceles triangles.

Applications

Elongated bipyramids are sometimes used as dice, especially to make dice with atypical side count, such as 5 or 7. Such a die has numbers written on the square faces, which are usually heightened into rectangles for convenience in rolling. Whichever number comes face-up when the die is rolled is the side that is to be read.