Jingle Shell, Windowpane Shell, or Mermaid's Toenail
Kingdom: Animalia, Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Anomiidae, Genus: Anomia, Species: Anomia trigonopsis · Anomiidae (Jingle shells) · Bivalve; single valve (likely the upper/left valve); translucent, irregular disc shape.
Species
Anomia trigonopsis
Shell Type
Bivalve; single valve (likely the upper/left valve); translucent, irregular disc shape.
Family
Anomiidae (Jingle shells)
Size
Approximately 30-40mm in diameter. This is a standard size for a mature specimen of this species, which typically ranges from 20mm to 60mm.
Color & Pattern
Translucent olive-green to smoky grey with yellowish undertones. It displays a distinct pearly or nacreous luster. The growth lines are visible as concentric, slightly irregular waves. Some white calcification is present near the umbo (hinge area).
Rarity
Very Common. These are frequently washed up on beaches in the Moreton Bay region, including Sandgate and Brighton.
Habitat
Marine, intertidal to shallow subtidal zones. They are typically found attached to hard substrates like rocks, other shells, or jetty pilings in protected bays and estuaries.
Geographic Range
Common throughout the Indo-Pacific, specifically abundant along the coastlines of Australia (including Queensland/Brisbane areas) and New Zealand.
Description
A delicate, translucent bivalve shell with a characteristic 'jingle' sound when several are shaken together. This specimen is thin and slightly convex, featuring a shimmering, mica-like texture. The exterior is relatively smooth compared to oysters but follows the irregular contour of the surface it was once attached to.
Key Features
Translucency (light passes through it), pearly luster, irregular circular shape, and a lack of heavy ribs or spines. The shell feels surprisingly light and paper-thin compared to most other bivalves.
Collector Value
Minimal monetary value (typically less than $1) but high aesthetic value for beachcombers. They are popular for use in wind chimes, jewelry, and decorative shell crafts due to their translucency and sound.
Condition Notes
Fair to Good. The shell is mostly intact but shows some chipping at the margins, which is common for such a fragile species. There is some minor surface erosion and salt crusting near the hinge.
Interesting Facts
The animal attaches itself to rocks via a calcified bundle of fibers called a byssus that passes through a hole in the lower (right) valve. In some cultures, larger related species (Placuna) were used as windowpanes before glass became widely available because of their translucency.
Ecological Role
Suspension feeders that filter plankton from the water column, helping to clarify coastal waters. They provide habitat for tiny encrusting organisms and are occasional prey for predatory gastropods and shorebirds.
Similar Species
Placuna placenta (Windowpane oyster), which is much larger and flatter, and Monia zelandica (Saddle oyster), which tends to be more opaque and distorted.
Beach Finding Tips
Look along the high tide line at Sandgate after a storm or strong easterly winds. They are often found mixed in with shell grit and seagrass debris. Their shine makes them easy to spot when the sun hits the wet sand.
Notes
Brighton Sandgate beach in Brisbane