[foobarbecue]

Interesting. I wonder why the five pentagons were needed. Is that because hat can't tile a sphere? Or some other requirement when assembling the ball?

[gilleain]

Well you cannot tile a sphere with just hexagons, you need a minimum of 5 pentagons.

Oh, from https://en.wikipedia.org/wiki/Fullerene:

"A closed fullerene with sphere-like shell must have at least some cycles that are pentagons or heptagons. More precisely, if all the faces have 5 or 6 sides, it follows from Euler's polyhedron formula, V−E+F=2 (where V, E, F are the numbers of vertices, edges, and faces), that V must be even, and that there must be exactly 12 pentagons and V/2−10 hexagons. "

So I'm not sure.

[zokier]

I would be really surprised if hat (or spectre) could tile sphere. Afaik most tilings of planes do not work on spheres.