Kidney Stone (image) Washington University School of Medicine Caption Pictured is the surface of a kidney stone with calcium oxalate crystals. Credit Wikimedia Commons, E.K. Kempf Usage Restrictions Credit to Wikimedia Commons, E.K. Kempf 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.