Pyritized Stromatolites (IMAGE) University of New South Wales Caption Photomicrograph of pyritized stromatolites from the 3.5 billion-year-old Dresser Formation. The stromatolites are delineated by pyrite, also known as fool's gold. Credit UNSW Sydney Usage Restrictions Credit UNSW Sydney License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.