Planorbella

Planorbella is a genus of freshwater air-breathing snails, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails, or planorbids, which all have sinistral, or left-coiling, shells. The Planorbella genus is not known to be colonial but are very plentiful and occur in large groupings. This genus is commonly found within North America, and is also found within various countries in Europe, including Iceland, Spain, Germany, France, Ukraine, and others. Over time, an increased amount of unintentional releases of the snails has led to Planorbella being found in more non-native areas like Siberia.

Some of the earliest fossil records date back to the Miocene.