Rocks containing biologically relevant organic molecules (IMAGE) University of Cologne Caption 3.5 billion-year-old barite (bottom) with fossilized microbial mat (top). This barite is part of the Dresser Formation in NW Australia. Credit Helge Missbach Usage Restrictions None 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.