Paludinella semperi is a species of minute salt marsh snail with an operculum an aquatic gastropod mollusk or micromollusk in the family Assimineidae. This species is found in Marshall Islands and Palau. Given a list of categories: company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, what category does the paragraph belong to?
Animal