Atlantic Marginella, Common Marginella
Phylum: Mollusca, Class: Gastropoda, Order: Neogastropoda, Family: Marginellidae, Genus: Prunum, Species: apicinum · Marginellidae (Margin Shells or Marginellas) · Gastropod (univalve); ovate/cylindrical spiral shell
Species
Prunum apicinum
Shell Type
Gastropod (univalve); ovate/cylindrical spiral shell
Family
Marginellidae (Margin Shells or Marginellas)
Size
Approx. 10-12mm (0.4-0.5 inches). This is a mature size for this species, which usually tops out around 15mm.
Color & Pattern
Base color is a creamy white to tan with three faint to distinct brown spiral bands. The shell possesses a high gloss. The specimen pictured shows rich reddish-brown banding and a light-colored apex. The gloss is natural for this family as the animal covers the shell with its mantle.
Rarity
Common; frequently found in shell drift and along the wrack line, though their small size makes them easy to miss.
Habitat
Intertidal and shallow subtidal zones. Prefers sandy bottoms, seagrass beds, and the vicinity of oyster reefs.
Geographic Range
Western Atlantic: North Carolina down through Florida, the Gulf of Mexico, and the Caribbean to the West Indies.
Description
A small, smooth, and highly polished teardrop-shaped shell. It features a low, blunt spire and a long, narrow aperture that extends nearly the full length of the shell. The outer lip is thickened (varixed) and the columella displays four distinct folds or 'teeth' characteristic of the genus.
Key Features
High glossy finish; four columellar folds; thickened outer lip; three brownish bands; tiny size and ovate-conic shape.
Collector Value
Low monetary value ($1-$3) but high aesthetic value for 'micro-shell' enthusiasts. Its value lies in its pristine gloss and representative banding.
Condition Notes
The specimen is in Good to Fine condition. It retains vibrant color and significant gloss, though there is some slight erosion or 'beach wear' at the apex. No major chips are visible on the lip.
Interesting Facts
Marginellas are often called 'rim shells' because of their thickened outer lips. In life, the animal's mantle completely covers the shell, protecting it from abrasions and acidic water, which is why beach-found specimens often still look freshly polished.
Ecological Role
Active predators and scavengers. They use their radula to feed on other small invertebrates and organic detritus. They are an important link in the sandy-bottom food web.
Similar Species
Prunum roscidum (Dewy Marginella) which is usually larger and more speckled/spotted; Volvarina avena which is much more slender and cylindrical.
Beach Finding Tips
Look in 'shell hash' piles at low tide. They are often concentrated in the fine debris just above the water line or caught in the roots of washed-up sea oats and sargassum.
Notes
Holden Beach, NC