Here's how this one works. I was sitting at home, looking at Zaarock's stuff, when I realized...

"Heads are round!"

This may not make sense to you, but it's quite simple, really. If heads are already round, why is everyone else trying to make things round to fit on the head? Nay, find a round thing to fit on the head instead. No warping, always comes out perfect.

I found some round things, and I'll be giving them away. Yes, giving. I've decided that credits are fun, but they're not everything.

Now as a background...

These 4 heads are all planetary bodies, and one universal observation. Enceladus, Europa, and Iapetus are all moons, Eurpoa being Jupiter's, Enceladus and Iapetus being Saturn's. The cosmic microwave background radiation is a study of all the interference waves emitting from various sources in the universe.