It's happening in our tank right now! A blue legged hermit is in the process of "evicting" a poor turbo snail. We've noticed quite a few of our turbo's have surprisingly blue legs! There are a bunch of empty transitional shells in the tank, but for some reason they are ending up in the snail shells. I'm not sure if the empties I have are too big or what, but to answer your question, it does happen.