Coober Pedy, South Australia Coober Pedy, a small town in South Australia is famous for its high quality Lower Cretaceous opals. The rarely found opalized fossils are the most highly value by collectors. This original salmon pink sandstone contains 21 opalized clam shells of several species including Cyenopsis species and mussel shells of Eyrene species. The largest clam shell measures 3 inches. The opalization process takes millions of years to replace the original shell material with the fire opal. The shells are just as found and unpolished. If polished the greens, oranges and purple opal would be revealed. Large assemblages such as this are usually only found in museums. Measuring 10 x 8 x 4 in