Earlier this year, a team of physicists set out to prove that it was a natural function of turbulence, and produced a lab simulation of the hexagon.
Quote:
Apparently, these shapes are not uncommon in fluid dynamics and can even be seen in hurricanes. This seems to be an example of a well-known phenomenon in one field being relevant to another in a completely unexpected way. But it takes a while for each community to be aware of the other one's results.