The Opalised Fossils stamp issue presents four opalised fossils from the Early Cretaceous Period, around 100 million years ago. In addition to the opalised moon snail from the South Australian Museum’s Fossil collection, three other fossils are showcased from the collections of the Australian Opal Centre - an opalised pine cone, an opalised dinosaur tooth and an opalised wood fragment.

Senior Collections Manager of Earth Sciences at the South Australian Museum, Ben McHenry, says the best quality opal is often found in fossils, as can be seen in the example of the moon snail.

“Dug from an opal mine at Coober Pedy, in life this moon snail (Euspira reflecta) was an active sea-floor predator preying on sessile bivalves such as mussels and cockles. Using its file-like teeth it would drill a hole through the protective bivalve shell and eat its victim from the inside out,” Mr McHenry explained. 

Modern moon snails are alive today and both their shells and crescent shaped jelly egg masses are commonly found along Adelaide’s beaches.

“Over millions of years the moon snail was opalised through a lengthy process where the original fossil was dissolved by acidic groundwater and created a large void which was later filled with opal deposited from super saturated siliceous fluids,” adds Mr McHenry.

The South Australian Museum holds the world’s largest public collection of Australian precious opal and devotes an entire display gallery to its famous opalised fossils including the much-loved Addyman Plesiosaur – the finest known opalised skeleton on Earth.

Australia Post Philatelic Manager Michael Zsolt said the postal service was proud to work with The South Australian Museum and The Australian Opal Centre on the stamp issue, designed by the Australia Post Design Studio’s Simone Sakinofsky.

“Fossils provide important insights into life on Earth, and Australia is a rich source of opalised fossils. The four specimens featured on the stamps highlight key locations where these incredible fossils are found, and the stamp designs showcase the beauty and wonder of Australia’s national gemstone,” he said.

The moon snail will be on special display in the Opal Fossils Gallery of the South Australian Museum from Monday 17 August and visitors will be able to buy the Opalised Fossils stamp packs from the South Australian Museum Shop. The full issue of Opalised Fossils stamps and collectables are also available from participating Post Offices, via mail order on 1800 331 794 and online at auspost.com.au/stamps, while stocks last.

“I’m excited and proud to share the moon snail with visitors both near and far with the introduction of this special edition stamp. Opal Fossils are one of the nation’s wonders and this is a great chance to deliver their story to all Australians,” Mr McHenry said.