Six sided weirdness on Saturn

I got home from school tonight and was greeted with a phone call from a friend who was telling me about a "weird hexagon on Saturn" that he had just learned about on the Discovery channel.

Being conspiratorially inclined, I was online in seconds, looking at space.com (because that is what nerds like myself do).
Lo and behold, there it was. According to NASA it is 15,000 miles across (big enough to fit 4 earth's in it) and according to the GIF above, it spins in a counter clockwise fashion.


What in the heck could cause something like that? They said that they have known about it for over twenty years and it is still there, so it is a "long-lasting oddity."

From Space.com:
"This is a very strange feature, lying in a precise geometric fashion with six nearly equally straight sides," said Kevin Baines, atmospheric expert and member of Cassini's visual and infrared mapping spectrometer team at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We've never seen anything like this on any other planet. Indeed, Saturn's thick atmosphere, where circularly-shaped waves and convective cells dominate, is perhaps the last place you'd expect to see such a six-sided geometric figure, yet there it is."