Assassin Snail Species Profile:
 
Common Name: Assassin Snail
Species name: Anentome helena
Species Group: Snail
Origin: Southeast Asia
Maximum Size: Approx. 2.5cm
Diet: Carnivore; it preys on other snails, and should be supplemented with sinking protein foods like bloodworms or sinking pellets.
Ideal Water temp: 22 - 27 degrees C
PH: 7.0 -> 8.0
 
Temprement:
Peaceful with fish and plants, but predatory towards other snails. Prefers a fine, soft substrate like sand for burrowing.
 
TNT Notes:
If you have a pest snail problem these are definitely worth looking at. 
Its worth noting the assassin snail will also breed in your aquarium.