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