https://phys.org/news/2018-05-history-saturn-small-moons.html > Martin Jutzi and Adrien Leleu, both members of the NCCR PlanetS, took the challenge of calculating the formation process of the small inner moons of Saturn. The first, simple tests worked well. "But then, we took the tidal forces into consideration and the problems piled up," remembers Adrien Leleu. "The conditions close to Saturn are very special," confirms Martin Jutzi. Since Saturn has 95 times more mass than Earth and the inner moons orbit the planet at a distance of less than half the distance between Earth and Moon, the tides are enormous and pull almost everything apart. Therefore, Saturn's inner moons couldn't have formed with these peculiar shapes by gradual accretion of material around a single core. An alternative model called pyramidal regime suggests that these moons were formed by a series of mergers of similar sized little moonlets. > Having solved their initial problems, the researchers could verify the pyramidal regime, but even more: They showed that the collisions of the moonlets resulted in exactly the shapes imaged by Cassini. Close to head-on mergers lead to flattened objects with large equatorial ridges, as observed on Atlas and Pan. With slightly more oblique impact angles, collisions resulted in elongated spaetzle-like shapes that closely resembled the 90-km long moon Prometheus as it was photographed by Cassini.