
https://saturn.jpl.nasa.gov/news/3005/cassini-reveals-strange-shape-of-saturns-moon-pan/
Since Cassini is going to do the death plunge in ~6 months, they're getting closer to the rings and some of the tiny moons, including 35km Pan. The most popular theory for the Space Ravioli shape right now is that the ridge is dust from the rings that have accumulated on Pan's equator. Some of Saturn's other moons also have a central ridge, but most aren't this extreme.