Fat Nassa

Caesia perpinguis

Caesia perpinguis is a marine gastropod that features an ovate-acute shell with approximately 5½ whorls. The shell is rounded and has a cancellated surface, characterized by nodulous longitudinal striae, particularly prominent near the top. A deep sulcus is present behind the aperture, and the outer lip is striated on the inside. A notable color variant of this species displays two broad spiral bands of deep chestnut against a grayish-buff shell, with one band located just below the suture and another around the periphery. This species is found in regions such as Magdalena Bay on the western coast of Mexico and the Persian Gulf, typically inhabiting sandy or muddy bottoms. It can be encountered at depths ranging from shallow waters to around 90 meters, with a significant number of occurrences reported shallower than 40 meters. The Fat Nassa feeds on small invertebrates and organic matter, contributing to the benthic ecosystem's nutrient cycling. Breeding behaviors are not detailed in the sources, but like many gastropods, they may exhibit hermaphroditic traits. Divers may find this species resting on the substrate, and its distinctive shell can aid in identification during dives.