Scotch Bonnet
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Cassidae, Genus: Semicassis, Species: S. granulata · Cassidae (Helmet and Bonnet shells) · Gastropod (univalve); Spiral/Globose shape. This appears to be a whole shell missing the animal.
Species
Semicassis granulata
Shell Type
Gastropod (univalve); Spiral/Globose shape. This appears to be a whole shell missing the animal.
Family
Cassidae (Helmet and Bonnet shells)
Size
Approximately 2.5 to 3 inches (65-75mm). This is a mature adult specimen, fitting well within the typical species range of 1.5 to 4 inches.
Color & Pattern
Pale apricot to brownish-orange base with several spiral bands of darker orange or tan squares. In this specimen, the pattern is slightly sun-bleached but the characteristic 'plaid' or checkered grid remains visible. The interior aperture is typically white with a glazed appearance.
Rarity
Common to Uncommon. While widely distributed, finding a large, whole specimen with its outer lip intact on a beach is a great find for a casual beachcomber.
Habitat
Subtidal marine environments; typically found on sandy bottoms at depths of 0 to 90 meters where it hunts for sand dollars.
Geographic Range
Western Atlantic: from North Carolina to Brazil, including the Gulf of Mexico and the Caribbean Sea.
Description
A medium-sized globose shell with a short spire and a large body whorl. The surface is sculpted with numerous spiral grooves and ridges, giving it a distinctive 'granulated' or textured feel. The outer lip is thickened and reflected, often bearing small teeth-like ridges (denticulations) on its inner edge.
Key Features
Checkered color pattern resembling a Scottish tartan; globose shape with a short, pointed spire; textured spiral grooves; and a thickened, enamel-like shield on the columella near the aperture.
Collector Value
Modest collector value ($5–$15 depending on perfect condition and lip integrity). It is highly desirable for regional collectors and beginner enthusiasts due to its iconic shape and state-shell status.
Condition Notes
Good collectibility grade. The shell is whole with visible color patterns, though it shows some minor beach-wear and natural fading/abrasion from sand. The apex and lip appear mostly intact.
Interesting Facts
The Scotch Bonnet is the official state shell of North Carolina. The living animal specializes in eating echinoderms, particularly sand dollars and sea urchins, by boring a hole through their skeletons with sulfurous acid and a specialized radula.
Ecological Role
Active predator of sand dollars and sea bisquits, helping to regulate populations of these burrowing invertebrates. It is not currently listed as endangered, but shell collection should be limited to empty specimens.
Similar Species
Semicassis cicricosa (Matted Bonnet), which has a more deeply pitted surface and much smaller spots, and Semicassis saburon (found in the Eastern Atlantic/Mediterranean).
Beach Finding Tips
Best found after coastal storms or heavy winter swells which wash them up from deeper sand bars. Look along the high-tide drift line among shell piles on the barrier islands of the Carolinas or the Florida Gulf Coast.