Hyperion, also known as Saturn VII, is a moon of Saturn distinguished by its highly irregular shape, chaotic rotation, extremely low density and its unexplained sponge-like appearance. It was the first non-round moon to be discovered. Wikipedia
Orbital period: 21 days
Radius: 83.885 mi
Discoverers: William Lassell, William Cranch Bond, and George Phillips Bond
Discovered: 1848