Octagrammic retroprism

The octagrammic retroprism, or stoarp, also called the octagrammic crossed antiprism, is a prismatic uniform polyhedron. It consists of 16 triangles and 2 octagrams. Each vertex joins one octagram and three triangles. As the name suggests, it is acrossed antiprism based on an octagram, treated as an 8/5-gon instead of 8/3.

Vertex coordinates
An octagrammic retroprism of edge length 1 has vertex coordinates given by:
 * (±1/2, ±($\sqrt{(6–2√2–√20–14√2)/8}$–1)/2, H),
 * (±($\sqrt{(2–2√2+√20–14√2)/2}$–1)/2, ±1/2, H),
 * (0, ±$\sqrt{4–2√2–2√146–103√2}$, –H),
 * (±$\sqrt{2–√2}$, 0, –H),
 * (±$\sqrt{2–√2}$/2, ±$\sqrt{(7–4√2+2√20–14√2)/3}$/2, –H),

where H = $\sqrt{2}$) is the distance between the antiprism's center and the center of one of its bases.