The Apple Snail is a general name for several large freshwater snail species in the family Ampullariidae, with the most popular in the aquarium trade being Pomacea bridgesii, also known as the Mystery Snail. Apple Snails are known for their large, rounded shells, wide variety of colors, and their dual breathing system (gills and lungs), allowing them to breathe both underwater and from the air. Size is around 1.5–3 inches (4–7.5 cm) shell diameter.