Question: the opening to the snail shell is known as the
Answer: Aperture : the opening of the shell Lip = peristome : the margin of the aperture Apex : the smallest few whorls of the shell Body whorl ( or last whorl ) : the largest whorl in which the main part of the visceral mass of the mollusk is found Columella : the `` little column '' at the axis of revolution of the shell Operculum : the `` trapdoor '' of the shell Parietal callus : a ridge on the inner lip of the aperture in certain gastropods Periostracum : a thin layer of organic `` skin '' which forms the outer layer o