Any spiral marine gastropod belonging to Turritella and
allied genera. These mollusks have an elongated, turreted shell,
composed of many whorls. They have a rounded aperture, and a horny
multispiral operculum.
1. The anterior or superior part of an animal, containing the brain, or chief ganglia of the nervous system, the mouth, and in the higher animals, the chief sensory organs; p...