drchasuble, is correct, they look like little white balls (rather like the ferterliser in compost), and when the eggs hatch the snails do indeed have their shells.
I only know this because I found some little white balls when I was repotting a plant, thought nothing of it and was disturbed one evening by this super loud crunching (I'm not exaggerating here, it was a cartoonish scronch scronching noise) and one had hatched and was chomping a hole in my fern. Little cute snails - great big loud mouths.