Slipper Snail (also known as the Slipper Limpet, Boat Shell, or Deckle Shell)
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Calyptraeidae, Genus: Crepidula, Species: Crepidula aculeata · Calyptraeidae (Slipper or Cup-and-Saucer shell family) · Gastropod (univalve); Cap-shaped/oval with internal shelf. This is an intact whole shell.
Species
Crepidula aculeata (Confidence: 85% based on location and sculpture)
Shell Type
Gastropod (univalve); Cap-shaped/oval with internal shelf. This is an intact whole shell.
Family
Calyptraeidae (Slipper or Cup-and-Saucer shell family)
Size
Estimated at 15-20mm in length. This is typical for the species; adults usually range from 10mm to 35mm.
Color & Pattern
External coloration shows concentric bands of mauve, reddish-brown, and creamy white. The specimen appears slightly naturally weathered. The internal shelf (not fully visible but inferred) is typically glossy white.
Rarity
Common; frequently found on beaches in South East Queensland, especially after storms or high tides.
Habitat
The species is marine-based, found in intertidal and shallow subtidal zones. It typically attaches itself to rocks, other shells, or hard substrates in relatively calm coastal waters.
Geographic Range
Found throughout the Indo-Pacific region, including the eastern and northern coasts of Australia (common around Brisbane/Moreton Bay), as well as warm-temperate waters globally.
Description
A small, low, cap-shaped shell with a slightly coiled apex located at one end. The exterior surface is characterized by irregular, scaly, or 'prickly' radiating ridges. Its most fascinating feature is internal: an arched horizontal shelf or rostrum that covers about half the aperture, giving it the appearance of a tiny slipper or a boat with a deck.
Key Features
The internal horizontal shelf (septum), the eccentric (off-center) apex, and the prickly or corrugated external ribs which distinguish the 'aculeata' species from smoother Crepidula species.
Collector Value
Minimal monetary value (typically $1-$5 for high-quality sets), but highly desirable for educational collections and artisanal crafts due to their unique 'slipper' anatomy.
Condition Notes
Good condition. The exterior sculpture is still visible despite some minor beach wear (abrasion on the apex). The color remains vibrant, suggesting it was recently washed up. Collectibility grade: Fine.
Interesting Facts
These mollusks are sequential hermaphrodites; they often live in 'stacks' where the larger individuals at the bottom are female and the smaller ones on top are male. If the female dies, the largest male below her will change sex to become female.
Ecological Role
They are filter feeders, removing plankton and organic detritus from the water. While native to Brisbane, some species of Crepidula have become invasive elsewhere, outcompeting native filter feeders.
Similar Species
Crepidula fornicata (Common Slipper Limpet), which is smoother and lacks the prickly ridges; and Crepidula convexa, which is smaller and more convex.
Beach Finding Tips
Look in the 'wrack line' (the line of debris left by high tide) at Brighton Beach, Brisbane. They are often found attached to larger dead shells or inside the apertures of empty gastropod shells.
Notes
Brighton Brisbane