The rhombic dodecahedron is an extraordinary polyhedron! It occurs in nature: many crystals do indeed have this shape. It can be found in the plant kingdom, in pomegranate seeds, for example, which is why François Lo Jacomo calls it a granatohedron. It also appears in the animal kingdom: the bases of the cells in honeycombs have this shape too.
The first person known to have studied this twelve-faced convex polyhedron—each face being a rhombus whose long and short diagonals are in the ratio 2\sqrt{2}—seems to have been Johannes Kepler, in Hamonices Mundi (1619). But here we are not interested in the rhombic dodecahedron itself: it is its first stellation that demands our attention.

*Left: The rhombic dodecahedron from Hamonices Mundi.

Right: The first stellation.*