Unlike conventional ships with propellor shafts, Queen Mary 2 carries her motors and propellors in swivelling pods. As I was told on the carrier deck, never walk into a prop arc! These formations in Saturn's Rings are believed caused by objects with the mass of a 100 m satellite. They create wakes in the icy Rings, just as Queen Mary 2 creates wakes in liquid. The differing orbital velocities at different distances from Saturn pull these wakes into the propellor shape. Needless to say, these objects are well within the Roche Limit. It is a wonder if moons exist this close to Saturn, and are not pulverised by smaller particles impacting them.