Saddle Oyster, Jingle Shell
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Anomiidae, Genus: Anomia, Species: Anomia trigonopsis · Anomiidae (Jingle shells or Saddle oysters) · Bivalve; specifically the upper (left) valve. The shell is irregular, thin, and translucent with a flattened, scale-like shape.
Species
Anomia trigonopsis (Common Saddle Oyster)
Shell Type
Bivalve; specifically the upper (left) valve. The shell is irregular, thin, and translucent with a flattened, scale-like shape.
Family
Anomiidae (Jingle shells or Saddle oysters)
Size
Approximately 25-35mm in length. This is a mid-sized specimen; the species typically ranges from 20mm to 60mm.
Color & Pattern
Shows an iridescent pearly interior with shades of silvery-grey, faint blues, and chalky white. The exterior (visible at edges) is dull greyish-green or brown. The colors are slightly muted/natural, showing typical beach-worn nacreous luster.
Rarity
Very Common. These are frequently found washed up on debris lines at Brighton Beach and similar sandy/muddy flats in Brisbane.
Habitat
Coastal marine environments, typically found in intertidal and shallow subtidal zones. They attach themselves firmly to hard substrates like rocks, other shells, or jetty pilings using a calcified byssus.
Geographic Range
Common throughout the Indo-Pacific region, including the eastern and southern coastlines of Australia (specifically prevalent around Brisbane/Moreton Bay) and New Zealand.
Description
A delicate, translucent valve with a characteristic 'jingle' when shaken with others. The shell is thin and pliant, often taking the shape of the object it was attached to. The interior surface features a distinct lustrous nacre (mother-of-pearl) and a visible muscle scar near the center.
Key Features
Translucency (light passes through), irregular wavy margins, and a distinct pearly interior. The absence of a hole in this specific valve indicates it is the upper valve (the lower valve has a circular hole for the byssal attachment).
Collector Value
Minimal monetary value (less than $1 USD). However, they are highly desired by crafters for wind chimes and jewelry due to their translucency and iridescent colors.
Condition Notes
Fair to Good. The shell shows some edge chipping and surface erosion consistent with being tossed in the surf. It lacks the 'Gem' quality found in live-taken specimens but retains its diagnostic pearly interior.
Interesting Facts
Known as 'Jingle Shells' because they make a metallic tinkling sound when carried in a pocket or bag. They are biological masters of camouflage, often perfectly mimicking the texture of the rock or oyster shell they grow upon.
Ecological Role
Filters huge amounts of seawater for plankton, helping to maintain water clarity. They provide habitat for tiny encrusting organisms and serve as a calcium source for the environment after they die.
Similar Species
Monia zelandica (which is usually larger and more circular) and various Placuna species (Windowpane oysters), which are much flatter and more fragile.
Beach Finding Tips
Look along the high tide mark after a storm or strong easterly winds. They are often found mixed in with shell grit and seaweed. Brighton Beach's muddy-sand flats at low tide are ideal locations.
Notes
Brighton beach at Brisbane . Shows inside of shell.