Prometheus and Amalthea were once thought to be the only ones, but it is now known that Cordelia, Ophelia, and a few others serve this function as well. All of these tiny moons lie just beyond a distance known as the Roche limit, and it is thought that if they drift any closer, they will be torn apart by the planet's gravity. FTP, name this special type of satellite whose 
Prometheus and Amalthea were once thought to be the only ones, but it is now known that Cordelia, Ophelia, and a few others serve this function as well. All of these tiny moons lie just beyond a distance known as the Roche limit, and it is thought that if they drift any closer, they will be torn apart by the planet's gravity. FTP, name this special type of satellite whose own  gravitational fields hold planetary rings together.
Prometheus and Amalthea were once thought to be the only ones, but it is now known that Cordelia, Ophelia, and a few others serve this function as well.
{Shepherd} moons (prompt on "moons inside rings" or the equivalent)