Ancylus fluviatilis
The river limpet ( Ancylus fluviatilis ) is a species of very small , freshwater , air-breathing limpet , an aquatic pulmonate gastropod mollusk in the tribe Ancylini within the family Planorbidae , the ram's horn snails and their allies . 
<triplet> gastropod <subj> mollusk <obj> parent taxon <triplet> Ancylini <subj> Planorbidae <obj> parent taxon