6 nearly equal sides is hard to get naturally, unless this is a giant fractal.
You kidding? Hexagons are a very natural structure. Honeycombs, basalt columns, bubble rafts. Not to mention lots of crystalline structures. Toss a bunch of marbles in a shoebox, and they will pack into a hexagonal array.
The photo looks to me like there are circulating atmospheric cells surrounding the hex pattern, which is distorted by the action of the cells from circular to hexagonal. Those cells create fluid motion that "sucks" the hex boundary outward at its corners, apparently.