This shape makes an interesting alternative to the traditional 8 sided die. It's made of two pyramids fused together.
It has a convex hull that's a tetragonal trapezohedron, an isohedron
. I embedded two pyramids inside each other to make this die. Its convex hull, a tetragonal trapezohedron, doesn't have parallel opposite sides, so this is a nice way to create an elegant 8 sided die.
Note that this is a blank, so the faces will need to be numbered. For more information on unique dice shapes, see http://loki3.com/poly/fair-dice.html