Biomineral Crystals Found in a Sea Urchin Tooth (image) National Science Foundation Share Print E-Mail Caption Geologic or synthetic mineral crystals usually have flat faces and sharp edges, whereas biomineral crystals can have strikingly uncommon forms that have evolved to enhance function. The image here was captured using environmental scanning electron microscopy and false-colored. Each color highlights a continuous single-crystal of calcite (CaCO3) made by the sea urchin Arbacia punctulata, at the forming end of one of its teeth. Credit Pupa U.P.A. Gilbert and Christopher E. Killian, University of Wisconsin-Madison Usage Restrictions None Share Print E-Mail 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.