Abalone Shell (image) University of California - San Diego Caption An abalone shell is made of thousands of layers of "tiles" made of calcium carbonate (more commonly known as chalk). A key to the strength of the abalone shell is a protein adhesive that binds to the top and bottom surfaces of the calcium carbonate tiles. The glue is strong enough to hold layers of tiles firmly together, but weak enough to permit the layers to slip apart, absorbing the energy of a heavy blow in the process. This pictures shows the tiles under various degrees of magnification. Credit Marc Meyers and Joanna McKittrick/Jacobs School of Engineering at UC San Diego Usage Restrictions Credit required 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.