Pentagonal double antitegmoid

The pentagonal double trapezohedroid is a convex isochoric polychoron with 100 order-5 truncated bi-apiculated tetrahedra as cells. It is the first in an infinite family of isochoric pentagonal trapezohedral swirlchora.

Being the dual of the grand antiprism, this shape is sometimes called the grand trapezohedron, in analogy to how trapezohedra are the duals of antiprisms. Despite this name, this shape is neither a stellation nor a trapezohedron in any common sense of the word.