Those we call black & white zebra turbos. They are from Belize. They get absolutely huge, and will cruise together if you have two.. but there is a danger with them. I had two giant ones as my only two snails in a semi aggressive tank. They were good, because no predator could knock them down, and they only came out at night when the fish were asleep.One day the water starting pouring over all 4 sides of the tank, one of them had climbed into the overflow and attached itself to the durso. After that I had to put up gutterguard as a snail fence to keep them out of the overflow...