Measuring up to 9 mm (about 0.35 inch), the Little Oat Marginella, Prunum bellulum (Dall, 1890) is a relatively common shallow-water species in the Caribbean and the tropical western Atlantic. The species has a relatively elongate shell, with the spire comprising about 1/7 of shell length. The aperture arrows posteriorly (“up” in the images), and the columella bears four folds, or plicae. The color is grayish- to blueish-white, and the shell surface in fresh or living specimens is smooth, glossy. This is a rare find on Sanibel, with at least one specimen found locally by Ken Piech, in 2014. The illustration shows a shell from Stock Island, near Key West.
