Shark Eye, Atlantic Moon Snail
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Naticidae, Genus: Neverita, Species: Neverita duplicata · Naticidae (Moon Snail family) · Gastropod (univalve); globe-shaped/globose spiral shell
Species
Neverita duplicata (formerly Polinices duplicatus)
Shell Type
Gastropod (univalve); globe-shaped/globose spiral shell
Family
Naticidae (Moon Snail family)
Size
Approximately 1.5 - 2 inches in diameter. This is a medium-sized specimen; adults typically reach 3 to 3.5 inches.
Color & Pattern
Naturally slate-grey to bluish-grey with hints of tan. This specific specimen appears heavily sun-bleached or weathered, resulting in a chalky, pale lavender-grey hue. The 'eye' (central umbilicus area) usually has a dark brown callus, though it is obscured or eroded here.
Rarity
Very Common. One of the most frequently found shells on Atlantic sandy beaches.
Habitat
Coastal marine environments; intertidal to shallow subtidal zones. They prefer sandy bottoms where they can burrow just beneath the surface to hunt.
Geographic Range
Western Atlantic, ranging from Massachusetts down to Florida and throughout the Gulf of Mexico.
Description
A smooth, robust, and globose shell with a low, flattened spire. The surface is characterized by fine growth lines. In a fresh state, it is glossy and polished, designed for gliding through sand. The shell is named for the distinctive 'eye' appearance of the umbilical callus on the underside.
Key Features
Compressed semi-globular shape; a very large, reaching body whorl; a wide, dark brown umbilical callus that almost completely covers the umbilicus; smooth texture with visible incremental growth striae.
Collector Value
Low (Under $5 USD). Because they are extremely common and this specimen is weathered, it holds primarily sentimental or educational value rather than commercial value.
Condition Notes
Fair condition. The specimen shows significant environmental wear, including 'chalking' (loss of the glossy protein layer), erosion of the apex, and minor chipping along the outer lip. It is a beach-worn find rather than a 'Gem' quality live-taken specimen.
Interesting Facts
Moon snails are predatory 'drills'. They use a specialized tongue (radula) and acid to bore perfectly round, beveled holes into other bivalves. They also create 'sand collars'—fragile, circular egg cases made of sand and mucus that are often found on the beach.
Ecological Role
Active carnivore and apex predator of the intertidal sandy flats. They help regulate populations of clams and other bivalves. They are in turn eaten by sea stars and various crab species.
Similar Species
The Northern Moon Snail (Euspira heros) is similar but lacks the large, dark brown callus covering the 'belly button' or umbilicus, and its shell is more globular and less flattened.
Beach Finding Tips
Look at low tide on flat sandy beaches, especially after a storm. Look for slight mounds or 'plow' trails in the wet sand where the snail might be burrowed just below the surface.