Buy one group of ten snails at the regular price and receive a second group of ten Free. By ordering 1, you will receive two groups of ten snails (20 snails total)The Nassarius Snail is a wonderful reef tank scavenger. These snails have a trunk-like tube they extend from their curved shells in order to hunt down food. The Nassarius will often times bury itself into the sand bed and wait until it senses food in its vicinity. They are good at keeping the top layer of the sand bed stirred up without damaging microfauna. They are great at removing detritus, uneaten food, and waste from the bottom of aquariums.