sentence1: Eoacmaea calamus is a species of sea snail , a true limpet , a true gastropod mollusk in the family Eoacmaeidae , one of the families of marine limpets .
sentence2: Eoacmaea calamus is a species of sea snail , a real limpet , a true gastropod mollusk in the Eoacmaeidae family , one of the families of naval limpets .