Atlantic Moon Snail (also known as Shark Eye)
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Naticidae, Genus: Neverita, Species: N. duplicata · Naticidae (Moon Snail family) · Gastropod (univalve); Spiral/Globose shape. This specimen is a heavily weathered fragment consisting primarily of the spire and upper whorls.
Species
Neverita duplicata (likely, 90% confidence based on regional prevalence and spire shape)
Shell Type
Gastropod (univalve); Spiral/Globose shape. This specimen is a heavily weathered fragment consisting primarily of the spire and upper whorls.
Family
Naticidae (Moon Snail family)
Size
The fragment appears to be approximately 1.5 to 2 inches in diameter. Fully intact adults of this species typically range from 2 to 5 inches.
Color & Pattern
The natural glossy grey-brown or 'shark-eye' blue-grey color has been mostly lost due to environmental exposure. It currently exhibits a sun-bleached, chalky off-white to cream coloration with some dark mineralization staining in the sutures and pits.
Rarity
Very Common. These are among the most frequently found predatory snail shells on South Carolina beaches, though finding a perfectly intact specimen with a glossy finish is more challenging.
Habitat
Found in marine environments, specifically in the intertidal and shallow subtidal zones. They prefer sandy substrates where they can burrow just beneath the surface to hunt for bivalves.
Geographic Range
Western Atlantic coast from Massachusetts to the Gulf of Mexico; very common in the Carolinas.
Description
A globose, sturdy shell with a low spire. This specimen shows a smooth, rounded whorl structure that tapers to a central apex. While the aperture and large body whorl are broken away, the coiled growth pattern of the Naticidae family is clearly visible, showing the characteristic 'moon' shape.
Key Features
Low, rounded spire; smooth surface lacking ribs or spines; a large umbilical callus (though mostly lost here) that typically covers the 'belly button' of the shell; and a rapid increase in whorl size.
Collector Value
Minimal monetary value ($0-$1) due to the broken and weathered condition. However, it is an excellent educational specimen for illustrating the internal spiral structure of gastropods and the effects of marine erosion.
Condition Notes
Poor to Fair. This is a partial shell/beach-worn fragment. It shows significant erosion, sun-bleaching, and 'clionid' sponge boring holes (the small black pits). The most fragile part—the outer lip and aperture—is missing.
Interesting Facts
Moon snails are formidable predators. They use a sandpaper-like tongue called a radula to drill perfectly circular holes into the shells of clams and other bivalves. If you find a clam shell with a tiny, neat hole near the hinge, it was likely eaten by this snail.
Ecological Role
High-level invertebrate predator that controls bivalve populations. Their egg cases, known as 'sand collars,' are often found on beaches and look like circular ribbons of stiff, sandy plastic.
Similar Species
Euspira heros (Northern Moon Snail), which has a deeper umbilicus and is found in cooler waters; Polinices lacteus (Milk Moon Snail), which is smaller and more porcelain-white.
Beach Finding Tips
Look along the high-tide line (wrack line) after a storm or at low tide on sandy flats. In Myrtle Beach, they are often found partially buried in the sand or among shell piles near piers.
Notes
Myrtle Beach in SC, broken shell