Granulose Topsnail

Calliostoma supragranosum

Calliostoma supragranosum is a small sea snail with a thin, conical shell that typically reaches heights between 6 mm and 15 mm. The shell is imperforate and consists of five convex whorls, featuring numerous fine spiral cords that are prominently beaded in the early whorls. The shell usually displays a light yellowish-brown color, often with irregular lighter markings, and may occasionally have pink or purple beads. The base of the shell is marked by distinct smooth concentric lirae, while the body whorl has a somewhat angular shape at the periphery. This species is found from Monterey Bay, California, to Asuncion Island in southern Baja California, Mexico, primarily inhabiting benthic environments at depths mostly shallower than 40 meters, with many occurrences at around 20 meters or less. Granulose Topsnails feed on algae and organic matter, utilizing a grazing behavior. They are gonochoric and typically reproduce by releasing their eggs into the water, where the embryos develop into planktonic larvae before becoming adults. Encountering this species while diving can be intriguing, as they often blend in with their surroundings due to their shell patterns. Divers should look for them on rocky substrates or among seagrass beds, where they can be relatively common. The conservation status of Calliostoma supragranosum has not been evaluated, but it has been recorded at multiple dive sites, indicating a notable presence in its range. Divers should respect their habitat and contribute to the conservation of marine ecosystems to ensure the continued survival of this species.