Moon Shell (Shark's Eye, Polinices, Natica)
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Naticidae, Genus: Neverita, Species: Neverita duplicata · Naticidae (Moon Snail family) · Gastropod (snail/univalve), whole shell, globular to dome-shaped
Species
Neverita duplicata (formerly Polinices duplicatus)
Shell Type
Gastropod (snail/univalve), whole shell, globular to dome-shaped
Family
Naticidae (Moon Snail family)
Size
Approximately 1 to 1.5 inches in diameter, which is a medium-sized specimen. Adults typically range from 1 to 3 inches.
Color & Pattern
Uniform milky white to chalky white coloration with subtle concentric growth lines. The color is completely bleached, likely from sun exposure and wave action. The interior and aperture are not visible.
Rarity
Very Common. This is a frequently encountered beach shell, especially along the eastern and Gulf coasts of the United States.
Habitat
Found primarily in shallow subtidal and intertidal zones, burrowing just beneath the surface of sandy bottoms, mudflats, and sandbars in marine environments.
Geographic Range
Western Atlantic Ocean, extending from Massachusetts along the coast of the United States down to the Gulf of Mexico and Florida.
Description
A smooth, globular, dome-shaped univalve shell with a low spire and a polished porcelain-like texture when fresh. This particular weathered specimen exhibits a classic chalky white appearance, rounded body whorl, and features a distinct circular predacious drill hole near the top, typical of attacks by other carnivorous snails.
Key Features
Globular shape, low spire, smooth exterior with fine growth lines, and often a distinctive callus covering part of the umbilicus (though obscured or weathered here). The presence of a circular borehole indicates predation.
Collector Value
Low to Moderate. While extremely common and generally of low monetary value as a beach find, moon shells are beloved by casual beachcombers and form a staple of introductory shell collections.
Condition Notes
Fair to Good condition. The shell is intact structurally except for a small drilled hole caused by a predatory snail and a slight chip at the base. It is completely sun-bleached white with loss of any natural brown or grey coloration.
Interesting Facts
Moon snails are formidable carnivorous predators that drill clean, countersunk holes into the shells of bivalves using a combination of acidic secretions and their radula to feed on the soft tissue inside. They secrete a distinct sand collar in which they lay thousands of gelatinous eggs.
Ecological Role
As apex benthic predators, moon snails play a crucial role in controlling bivalve populations and maintaining the balance of sandy intertidal ecosystems. Their discarded shells frequently provide essential housing for hermit crabs.
Similar Species
Atlantic Shark's Eye (Neverita duplicata) can be confused with other naticids like the Northern Moon Snail (Euspira heros), which tends to be taller and more spherical, or the Lettered Moon Snail.
Beach Finding Tips
Look along sandy ocean beaches and sandbars during low tide. Search the wrack line or gently sift through wet sand where moon snails burrow just below the surface, leaving small dome-shaped humps or disturbances.