sentence1: Patella swakopmundensis is a species of sea snail , a true limpet , a marine gastropod mollusk in the Patellidae family , one of the families of true limpets .
sentence2: Patella swakopmunden sis is a species of sea snail , a true limpet , a true gastropod mollusk in the family Patellidae , one of the families of marine limpets .