The Atlantic Morum, Morum oniscus (Linnaeus, 1767) has a very characteristic, thick and heavy (for its size) shell with a sculpture of three spiral "rows" of squarish knobs. Its color is whitish or light gray with brown patches. Some shells retain its softer outer, or periostracum, which is dark-gray, velvety. Morum snails were included in the Helmet shell family Cassidae until 1987, when malacologists Hughes and Emerson demonstrated that it belongs within the harp shell family Harpidae. The Atlantic Morum is not rare in the Caribbean, Bahamas, Florida Keys, and in deeper water in the Gulf of Mexico, where it thrives in coral habitats, but is very rare in SW Florida. The shell herein illustrated was found by Kimberly Nealon on Captiva, on August 7, 2010 (she found another Atlantic Morum this weekend in Sarasota).
The Atlantic Morum, Morum oniscus (Linnaeus, 1767).