This opalized shell from Australia is a rare and valuable find. Fossils from the time of dinosaurs are not commonly found in Australia. The country was covered by "The Eromanga Sea," a shallow inland sea, during the Cretaceous era, which spanned approximately one-third of its landmass. These particular pieces are estimated to be from the Paleocene period (656-56 million years ago) through the Eocene period (56-33.9 million years ago).