Scotch Bonnet Shell
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Cassidae, Genus: Semicassis, Species: Semicassis granulata · Cassidae (Helmet and Bonnet family) · Gastropod (snail/univalve), whole shell, ovate to inflated shape
Species
Semicassis granulata
Shell Type
Gastropod (snail/univalve), whole shell, ovate to inflated shape
Family
Cassidae (Helmet and Bonnet family)
Size
Approximately 3.5 inches, which is on the larger end of average for this species. Adults typically range from 2 to 4 inches in length.
Color & Pattern
Chalky white, completely sun-bleached with loss of the characteristic golden-brown checkerboard or banded patterns. The texture is heavily granular.
Rarity
Common
Habitat
Shallow subtidal zones to moderately deep waters, typically found on sandy bottoms, sand flats, and offshore bars.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina through the Gulf of Mexico, Caribbean, and down to Brazil.
Description
An attractive, stout shell featuring a low spire and a large, inflated body whorl. The surface is heavily sculptured with distinct spiral cords crossed by fine axial grooves, creating a pronounced grid-like or beaded texture. The outer lip is thickened and slightly flared, though worn in this specimen.
Key Features
Inflated body whorl, low spire, and heavily sculptured grid of spiral cords and beads covering the entire surface.
Collector Value
Low to moderate collectible value. While a staple for beachcombers, specimens lacking their natural golden-brown coloration and glossy finish are generally valued more for educational or decorative purposes than as high-grade collector items (approx. $2 to $10).
Condition Notes
Fair condition. The shell is structurally intact but thoroughly sun-bleached to a uniform chalky white, having lost all natural color patterns. Some minor wear on the sculpture and outer lip.
Interesting Facts
Scotch Bonnets are active predators that specialize in feeding on sea urchins and sand dollars, using their strong radula and acidic secretions to bore into or break down their prey.
Ecological Role
Acts as an important carnivore controlling sea urchin populations in benthic habitats. Empty shells frequently serve as essential mobile homes for hermit crabs.
Similar Species
Cassis madagascariensis (Emperor Helmet) and other Cassis species, which are generally much larger and possess a heavy shield-like callus on the parietal wall.
Beach Finding Tips
Best found after severe storms or heavy wave action along sandy beaches in the southeastern United States and the Gulf of Mexico, particularly during low tide.