I also feel like the moons were forming and Saturn's rings froze it in the process. Saturn's rings are made out of rocks and ice, anyways. Epimetheus is not in the rings and the texture looks normal, unlike the other moons.
I think that these moons were formed by Saturn's rings, since other planets don't have rings and their moons aren't misshaped (some of them). Plus, Atlas looks like a tiny version of Saturn, sincen it is inside of the rings just like Daphnis and Pan. This is just me made-up theory, and let's hope in the future I am correct! (I just turned 10!)