Shark's Eye, also known as Moon Snail or Atlantic Moon Snail
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Naticidae, Genus: Neverita, Species: N. duplicata · Naticidae (Moon Snail family) · Gastropod (univalve), whole shell, globular to low-spired spiral shape
Species
Neverita duplicata (formerly Polinices duplicatus)
Shell Type
Gastropod (univalve), whole shell, globular to low-spired spiral shape
Family
Naticidae (Moon Snail family)
Size
Approximately 2 to 2.5 inches in diameter, which is typical for an average adult specimen. Adult sizes generally range from 1.5 to 3 inches.
Color & Pattern
This particular specimen is heavily weathered and sun-bleached, presenting a uniform matte off-white to chalky gray coloration. Fresh specimens typically feature a brownish-gray to yellowish-brown exterior with a dark brownish-purple umbilicus area, but sun exposure has completely removed the natural organic pigments.
Rarity
Very Common. These shells wash ashore regularly on sandy beaches throughout their geographic range.
Habitat
Found primarily in shallow subtidal and intertidal zones down to moderate depths. They prefer sandy or muddy substrates where they can easily burrow just beneath the surface to hunt for bivalves. They are marine animals.
Geographic Range
Western Atlantic Ocean, ranging from Massachusetts down to the Gulf of Mexico, Florida, and parts of the Caribbean.
Description
A smooth, globose, and sturdy univalve shell featuring a low spire and a large, rounded body whorl. The surface is mostly smooth with faint growth lines. The specimen photographed is viewed from the apical/spire side, showing the compact, slightly raised spire winding down into the broad, rounded body chamber.
Key Features
Globular, almost spherical shape; low, compact spire; smooth exterior surface; heavy and solid construction designed to withstand wave action and predatory attacks.
Collector Value
Low collector value due to commonness and weathered condition. It is a wonderful educational piece for beginner beachcombers and children, but commands virtually no monetary value in the shell trade.
Condition Notes
Worn and sun-bleached condition. The outer periostracum and original coloration are completely absent due to weathering and tumbling in the surf. No major fractures or holes are visible from this angle. Collector grade: Fair to Good as a common beach find.
Interesting Facts
Moon snails are famous predators that drill clean, countersunk holes through the shells of other molluscs, particularly clams and bivalves, using their radula and acidic secretions to feed on the soft tissue inside. They are also known for creating sand collars—eggs mixed with sand and mucus—which harden into fragile, bowl-like structures.
Ecological Role
Moon snails act as important carnivorous predators in sandy benthic ecosystems, helping to regulate bivalve populations. They serve as a food source for various marine predators, and their vacated shells often provide essential temporary housing for hermit crabs.
Similar Species
Neverita lewisii (Northern Moon Snail), which grows significantly larger, and Euspira heros (The Northern Moon Snail), which tends to have a slightly more elevated spire.
Beach Finding Tips
Look along sandy ocean-facing beaches during low tide, particularly after storms or heavy wave action. Search the high-tide wrack line where lightweight empty shells and moon snail sand collars often accumulate.