Community of stem group eukaryotes (IMAGE) GFZ Helmholtz-Zentrum für Geoforschung Caption Artist’s imagination of an assemblage of primordial eukaryotic organisms of the ‘Protosterol Biota’ inhabiting a bacterial mat on the ocean floor. Based on molecular fossils, organisms of the Protosterol Biota lived in the oceans about 1.6 to 1.0 billion years ago and are our earliest known ancestors (credit: Orchestrated in MidJourney by TA 2023). Credit Orchestrated in MidJourney by TA 2023 Usage Restrictions Credit must be given to the creator. License CC BY 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.