Continuing with the saga of the large family Mangeliidae, Rubellatoma diomedea Bartsch and Rehder, 1939 reaches about 10 mm (0.4 inch) in length, and has distinctly angled whorls, and a typical “lozenge-shaped” shell. The sculpture includes about 7–10 rounded ribs per whorl crossed by fine spiral striations. The aperture comprises about half the shell length, and the color is white with a couple of broad spiral brown bands more evident on the last whorl.
