sentence1: Propilidium pelseneeri is a species of sea snail , a true limpet , a true gastropod mollusk in the Lepetidae family , one of the families of the marine limpets .
sentence2: Propilidium pelseneeri is a species of sea snail , a true limpet , a marine gastropod mollusk in the Lepetidae family , one of the families of the true limpets .