The snail that digs is the Malayan Trumpet Snail, commonly just called MTS. They're tiny little snails though, compared to the apple snails. They'll do wonders for your tank if it's a planted tank, supposedly.
Apple snails I adored because they were big and beautiful, and ate up any random fish food that fell to the bottom of the tank. I'm sure they stir up the substrate a little, but you'll probably still need to do it manually. It's really personal preference if you want to add them or not. And oh! Make sure you don't have any snail-eating fish if you intend to actually keep them around, haha.