Hermit crabs, especially blue legs love the taste of snail meat. They'll tell you they want a bigger shell, but even if you have empty shells around hermits don't like sticking to a vegetarian diet and they love to nibble on asterina snails.
The best hermits are scarlets, they will stick to their vegetarian diet until they get really big. Or buy tiger trochus snails, these snails can turn themselves back over when they fall and they're good at fending off hungry hermits. ;]