The onion nerite snail, also called the red onion nerite snail, has a round shell with brown and cream bands with black spots that could resemble onion rings. These nerite snails love to graze on algae in both freshwater and slightly salty tanks. They stay fairly small  and won’t reproduce in a regular aquarium. Onion snails are steady cleaners and with unique shell pattern that make them a popular pick for planted and nano aquarium setups.