That massive equatorial ridge is seriously weird. Iapetus also has one light colored side and a dark colored side. Ceres is out there from the sun and in a strange neighborhood. Thanks for posting the photo of Iapetus, I hadn’t seen any of this before.
The 6 kilometer equatorial ridge completely encircles the moon just to make it even odder. Early images, now removed, at NASA showed that the moon is not round but hexagonal ... and so may not be a natural body ...