new to the hobby and I noticed this guy in the tank.. He usually just stays to himself. However, he eats up other snails from time to time.. you can see in the picture he just ate up one of my new snails..
and he ate one of my turbo snails a week earlier.. should HE STAY OR GO!!!
I'm not a snail expert, but I'm pretty sure that's a whelk. Do a search on the site and you'll find all sorts of posts about it. It's a carnivore and will eat all your snails if it can manage and anything else it can find. Get it out.