HomeWhy do fish and other living things have different roles in the aquarium? What are the functions performed by snails?

What are the functions performed by snails?
      People often put snails in a tank because they eat algae that grow in the tank, which helps keep the glass clear. Snails also produce waste.  Sometimes when snails withdraw in their shells it is a sign that water conditions in an aquarium are getting bad (e.g. waste is not being recycled, too much build up of nitrogen compounds is occurring).