Personally, I think it is the join line, like what you see on cheap, plastic toys...
The moon's peculiar shape can be explained if the satellite moved in an eccentric oval-shaped orbit 100 million years after its violent formation, when the satellite hadn't yet solidified, the researchers say.
It was like a big ball of molasses and all around the equator it got deformed, study team member Ian Garrick-Bethell of the Massachusetts Institute of Technology told SPACE.com.
Around that time, conditions, such as orbit shape and position, were optimal for this "ball of molasses" to cool down and become the solid moon that we now know.
