Australian Windowpane Oyster or Jingle Shell fragment
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Placunidae (or Anomiidae) · Placunidae (Windowpane Oysters) or Anomiidae (Jingle shells) · Bivalve fragment; flat, translucent, and irregularly shaped calcified plate.
Species
Placuna placenta (Windowpane Oyster) or Monia zelandica/Anomia sp.
Shell Type
Bivalve fragment; flat, translucent, and irregularly shaped calcified plate.
Family
Placunidae (Windowpane Oysters) or Anomiidae (Jingle shells)
Size
Approximately 30-40mm in length. This is a partial fragment; the full adult length of a Windowpane Oyster can exceed 150mm.
Color & Pattern
Translucent white to off-white with some pearly iridescence. The surface is pitted with dark sponge-boring holes (cliona holes) and lacks defined color patterns due to heavy weathering and beach-bleaching.
Rarity
Very Common as fragments; whole specimens are uncommon on high-energy beaches but frequent in muddy bay areas.
Habitat
Low intertidal to shallow subtidal zones, typically found in muddy or silty sand substrates in estuarine or coastal waters like Moreton Bay.
Geographic Range
Indo-Pacific, common throughout the tropical and subtropical waters of Northern Australia and Queensland (including Brighton Beach, QLD).
Description
A weathered, calcified fragment of a translucent bivalve shell. The specimen shows a characteristic pearly lustre and thin, layered structure. It is heavily eroded with jagged edges and displays numerous small black pin-holes caused by boring sponges.
Key Features
Translucency, thin laminate structure, pearly interior, and the specific flat morphology associated with the Windowpane Oyster family.
Collector Value
Negligible. As a beach-worn fragment, it lacks the taxonomic value of a whole, high-quality specimen. Its value is primarily sentimental as a beach find.
Condition Notes
Poor/Fragmentary. This is not a complete shell but a beach-worn shard. It shows significant erosion, loss of original shape, and predator/boring damage. Collectibility grade: Poor.
Interesting Facts
In some cultures, specifically the Philippines, these shells are processed and used as a substitute for glass in windows ('Capiz shells'). They are also used for decorative handicrafts and jewelry due to their unique translucency.
Ecological Role
Filter feeders that help clear water by consuming plankton. When alive, they provide a hard substrate for other organisms to attach to in otherwise muddy environments.
Similar Species
Anomia ephippium (Common Jingle Shell) which is usually smaller and more convex, or other species of the Genus Placuna.
Beach Finding Tips
Look in the 'wrack line' after a high tide at Brighton Beach, specifically in areas where silt or mud meets the sand. Seek out flat, shimmering pieces that stand out against the opaque rocks and sand.
Notes
Brighton beach QLD