Iapetus is the third biggest moon of Saturn. Is nut-shaped moon because it has a range that splits the world in half. Other of the weird stuff of that moon is the colors, half moon is black brown and other half moon is white.
Based in this real photo [link]
and this other photo [link]
More information about Iapetus here -> [link]
I have retouch the light of the saturn and I have put the mooon Iapetus in front of them