Antillean Tusk Shell

Shell size to 13 mm; shell tubular, dull, chalky, or glossy. The shell starts out with nine primary ribs at the apex, but as it grows, three secondary ribs rapidly appear, for a total of 12 ribs. When the apex is broken off, leaving only the wider, younger parts of the shell, it is hard to tell which ribs are primary and which are secondary. Rib shape variable, ribs covered with fine longitudinal lines. Wide apical notch on convex or concave side sometimes present. Typically with grooves between ribs presenting regularly spaced "windows" of thinner shell material. Curvature not extremely pronounced. Color white, sometimes with a greenish tint. One shell found in December 2016 at Blind Pass, Sanibel, by Susan J. Hewitt. (Entry prepared in cooperation with Rebecca Mensch.)