Pacific Ogre Cup-and-Saucer Shell (fragment)
Phylum: Mollusca; Class: Gastropoda; Order: Littorinimorpha; Family: Calyptraeidae; Genus: Calyptraea · Calyptraeidae (Slipper shells and Cup-and-saucer shells) · Gastropod (univalve); Fragment of a cup-and-saucer snail with prominent internal septum.
Species
Calyptraea sp. (likely Calyptraea scutulum)
Shell Type
Gastropod (univalve); Fragment of a cup-and-saucer snail with prominent internal septum.
Family
Calyptraeidae (Slipper shells and Cup-and-saucer shells)
Size
Approximately 25-30mm in width. This represents a partial specimen; the full species typically reaches 30-50mm in diameter.
Color & Pattern
Chalky white to off-white. The exterior is heavily weathered and sun-bleached, losing the typical brownish radiating lines or flecks often seen in live specimens. The interior retains a slightly smoother, pearly texture within the 'cup' area.
Rarity
Common (as a species), though complete specimens are often overlooked due to their camouflage or fragile edges.
Habitat
Found in shallow marine intertidal and subtidal zones. They live attached to rocks, large shells, or other hard substrates where they filter-feed.
Geographic Range
Common across the Indo-Pacific, specifically recorded along the Queensland coast, including Moreton Bay and the Brisbane region (Sandgate/Brighton).
Description
This is a weathered fragment of a cup-and-saucer shell. It is characterized by its unique internal structure: a circular or semi-circular 'shelf' or septum that resembles a small cup inside the larger shell. The fragment shows heavy pitting and erosion, likely from being tumbled in the surf at Sandgate.
Key Features
The presence of the internal cup-like septum is the primary diagnostic feature. The shell is thin but sturdy, with tiny pin-prick pits (clionid sponge borings) visible on the surface.
Collector Value
Minimal. While the family is interesting to malacologists, broken and bleached fragments like this have no commercial value, though they serve as great local ecological indicators for beachcombers.
Condition Notes
Poor to Fair. This is a beach-worn fragment rather than a whole specimen. It is heavily eroded with jagged broken edges and lacks the apex of the shell. Collectibility grade: Poor (Geological/Study value only).
Interesting Facts
Mollusks in this family are protandrous hermaphrodites, meaning they begin their lives as males and later transition into females. They are sedentary filter feeders that rarely move once they find a suitable rock to cling to.
Ecological Role
Benthic filter feeders that help clear particulate matter from the water column. The holes in this specimen suggest it was a substrate for boring sponges after the snail died.
Similar Species
Crepidula (Slipper shells) which have a flat shelf rather than a cup, and Crucibulum (true Cup-and-Saucer shells) which have a more centered, distinct cup.
Beach Finding Tips
Look in shell drift lines after high tide at Sandgate. Search for small white discs that look like discarded pieces of ceramic; turning them over reveals the diagnostic internal cup.
Notes
Brighton beach Sandgate Brisbane