I think those are reef safe. Little snails that will breed in your tank and clean up the rocks for you.
I think they are these:
Stomatella Varia. - A very commonly found hitch hiker. Harmless herbivore which has a unique way of fooling predators. When attacked or pulled off the glass by us, it will drop a large portion of its foot, much like some lizards that break off their tails in an attempt to keep a predator busy while it makes its escape. Keeping to their descriptive species name, they are highly variable in colorations.
Here is a good site for hitchhikers.
http://www.chucksaddiction.com/Hitchsnails.html