Nacre (IMAGE) University of Wisconsin-Madison Caption Nacre, also known as mother-of pearl, is the biomineral that lines some seashells. New research shows it keeps a record of ancient ocean temperatures. Credit UW-Madison 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.