Wow, two snails in the same week that I can't identify. People are coming up with some really unusual stuff lately. It looks like it's probably a Melongena species, or something closely related, but I don't recognize it. I thought I could recognize pretty much all the snails in the Melongenidae, but maybe not. It has the characteristics of several different species in this family, but doesn't really match any of them. It should be predatory, but I'd be interested to find out what, if anything, it actually eats in your tank. If it were mine, I'd keep it unless I had some snails that I truly treasured and didn't want to risk. I'll check some books for it when I get back home.
Cheers,
Don