Lol had a grade 4 teacher tell me once that circles aren't natural and an invention of man kind. I figure she must have been a werewolf or something. Never actually seen a full moon or doesn't remember seeing it.

Yeah, I think it’s probally art teachers that would have more of a use for such a statement.

it was explained in an anime called Ruri Rocks.

it cristalizes into a cube as it cools. that's normal, but the cristalisation is exothermic. this makes the areas in the middle of the faces hotter than the edges, so it cannot cristalize in the centre of the faces and only on the cube edges.

it's explained better in that anime.