Astraea snails (often referred to as Astrea snails) These snails will consume film and hair algae on the glass and rocks in your aquarium. These Astraea ship at about the size of a nickel, they grow to the diameter of a quarter. These snails will consume film, some cyano species, and some of the finer hair algae on the glass and rocks in your aquarium. They are not the hardiest of creatures, because they cannot right themselves if turned upside down. They should be placed carefully into your aquarium. If you notice one got flipped over, you should act as quickly as possible to right them.