Claim: The Valvata piscinalis is a European valve snail that was introduced to Lake Ontario in 1897, and in 40 years, dispersed to Lake Erie.
Evidence: Valvata piscinalis, common name the European stream valvata or European valve snail, is a species of minute freshwater snail with gills and an operculum, an aquatic gastropod mollusk in the family Valvatidae, the valve snails. The European valve snail was originally introduced to Lake Ontario at the mouth of the Genesee River in 1897. In forty years it dispersed to Lake Erie and subsequently it expanded its range to the Saint Lawrence River, the Hudson River, Champlain Lake and Cayuga Lake.