fossilized snail shell (IMAGE) University of Texas at Austin Caption A 250-million-year-old fossil of a marine snail shell in pristine condition. The shell was one of the thousands examined in the study. Scale bar = 100 µm Credit William Foster et al. 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.