Colorful Opalized Crayfish Gastroliths Fossils

Decapoda indet. Fossils

Phylum Arthropoda, Subphylum Crustacea, Class Malacostraca, Order Decapoda

Geological Time: Early Cretaceous, Albian Stage

Size (25.4mm=1 inch): Yellow: 15 mm across Purple: 17 mm across

Fossil Site: Griman Creek Formation, Wallangulla Sandstone Coocoran Opal Field, Lightning Ridge, New South Wales, Australia

Code: AAF498

Price: Sold


Description: These colorful specimens come from Lightning Ridge in Australia, a region renowned for its opal production. Coober Pedy, Andamooka, White Cliffs, and Lightning Ridge are the 4 most famous sources of Australian opals. Indeed, Lightning Ridge is known as the black opal capital of the world. It is the alignment of the hydrated silica spheres which ultimately results in the rainbow effect of precious opal, the result of deflection and diffraction of light as it passes through the planes of hydrated silica molecules. The size of the spheres impacts the colors seen, with smaller spheres resulting in blues and larger spheres in reds. The opalized state of these unusual fossils shows you something of the palette of colors attainable. These are fossil gastroliths from a crayfish. Today such gastroliths are found in freshwater crayfish of the family Astacidae as paired disc-shaped structures. They are thought to be the way the animal sequesters calcium prior to ecdysis (molting) as a way of conserving this precious resource The gastroliths are then broken down to facilitate hardening of the new exoskeleton. Many types of opalized fossils have been found, from individual dinosaur bones and belemnites, to entire opalized Plesiosaur skeletons valued in excess of a million dollars.

Fossil Sales


Fossil Mall Navigation:
l Home l Fossils for Sale Map l Museum and Rare Fossils l How to Buy Fossils l

Navigate by Fossil Category:
l Trilobites
l Ammonites l Fish Fossils l Invertebrate Fossils l
l Crinoids and Echinoderms l Insect Fossils l Dinosaur and Reptile Fossils l
l Cambrian Explosion Fossils l Plant Fossils l Stromatolites l
l Vertebrate Fossils l Fossil Amber l Trace & Ichnofossils l

l Fossils and Paleotological Science Information l