Elongated square bipyramid

In geometry, the elongated square bipyramid (or elongated octahedron) is the polyhedron constructed by attaching two equilateral square pyramids onto a cube's faces that are opposite each other. It can also be seen as 4 lunes (squares with triangles on opposite sides) linked together with squares to squares and triangles to triangles. It is also been named the pencil cube or 12-faced pencil cube due to its shape.

Elongated square bipyramid
Type	Johnson J14 – J15 – J16
Faces	8 triangles 4 squares
Edges	20
Vertices	10
Vertex configuration	${\displaystyle 2\times 3^{4}+8\times (3^{2}\times 4^{2})}$
Symmetry group	${\displaystyle D_{4h}}$
Dual polyhedron	square bifrustum
Properties	convex
Net

A zircon crystal is an example of an elongated square bipyramid.