A bipyramid
A bipyramid with pentagonal base. It is a polyhedron with equal faces; moreover, the group of symmetry is transitive on the faces, this means that, if we take any couple of faces of a polyhedron, there's a symmetry of the polyhedron that sends the first face into the other one. For this reason, it could be used as a impartial die.
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The image belongs to the sections...:
Prisms, antiprisms, pyramids, dipyramids (3D geometry)