So far NASA has counted 63 definitive Moons around Saturn, and named them all.
However one small moon named, Methone: has been found to have no craters on its surface, after a flybye.
Very unusual.

http://apod.nasa.gov/apod/ap121106.html

Considering the vast expanse of empty space, it always surprises me that there are so many impact craters out there. Perhaps this little “egg” really has escaped.