Scotch Bonnet Fragment (Atlantic Scotch Bonnet)
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Cassidae, Genus: Semicassis, Species: Semicassis granulata · Cassidae (Helmet and Bonnet family) · Gastropod (univalve) fragment, specifically a portion of the body whorl showing spiral sculptural cords
Species
Semicassis granulata
Shell Type
Gastropod (univalve) fragment, specifically a portion of the body whorl showing spiral sculptural cords
Family
Cassidae (Helmet and Bonnet family)
Size
The fragment measures approximately 2.5 inches in length. Whole adults of this species typically range from 2 to 4 inches.
Color & Pattern
Cream to pale off-white base with characteristic faint orange-brown spiral banding corresponding to the raised cords. Shows some natural weathering and a small darker spot on the right side.
Rarity
Common as a species, but whole specimens are prized finds; this specific fragment is very common on beaches within its range.
Habitat
Shallow subtidal waters, typically found on sandy bottoms, offshore bars, and seagrass beds from the low tide mark down to about 150 feet.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina through the Gulf of Mexico, the Caribbean, and down to Brazil.
Description
An oblong fragment of a marine snail shell displaying pronounced, rounded spiral ribs (cords) running horizontally across the surface. The texture is smooth yet strongly ridged, representing part of the robust body whorl of a bonnet shell.
Key Features
Strong, rounded spiral ribs with low profile and characteristic orange-brown coloration restricted to the cord ridges, separating it from other similar gastropod fragments.
Collector Value
Low value due to being a broken fragment. Whole, gem-quality specimens are moderately sought after by collectors and commonly sold in coastal shell shops.
Condition Notes
Fragmentary condition with smoothed, wave-worn edges. Colors are well-preserved with light sun bleaching. Overall collectibility grade: Fair to Good as a craft or study piece.
Interesting Facts
Bonnet shells are active predators that specialize in feeding on sea urchins and sand dollars, using their acidic secretions and radula to bore through tests.
Ecological Role
Acts as an important carnivorous predator controlling sea urchin populations in benthic marine communities. Shells provide homes for hermit crabs after the original owner dies.
Similar Species
Other helmet and tun shell fragments (Cassidae and Tonnidae families), which can be distinguished by different rib counts and spacing.
Beach Finding Tips
Look along high-tide shell lines on sandy barrier island beaches after storms or rough surf, particularly in the southeastern United States and Gulf Coast.