Seen last week. A mackerel sky? Or like waves on a beach or ripples in sand. One thing mimics another. There are only a few shapes in the world, so there is repetition. The Greeks had shapes that nested inside each other called platonic solids.

Wikipedia says:

The ancient Greeks studied the Platonic solids extensively. Some sources (such as Proclus) credit Pythagoras with their discovery. Other evidence suggests that he may have only been familiar with the tetrahedron, cube, and dodecahedron and that the discovery of the octahedron and icosahedron belong to Theaetetus, a contemporary of Plato. In any case, Theaetetus gave a mathematical description of all five and may have been responsible for the first known proof that no other convex regular polyhedra exist.

That went off on a bit of a tangent!