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Two North American freshwater snails of the species Planorbella trivolvis (synonym: Helisoma trivolvis) in a habitat with floating water weeds, which they prefer. These snails have shells up to 18 mm in width, and are sometimes seen in aquaria.

These snails belong to the family Planorbidae, the ramshorn snails, which are known for their planispiral, left-coiled shells, for having the red blood pigment hemoglobin, and also as intermediate hosts for various parasites, including medically important ones.