Claw like Device Open (IMAGE) University of California - San Diego Caption In this paper, one finding was the importance of a T-shaped structure running down the middle of each of the urchin's teeth, called the keel. Simulations show that teeth with keels experienced 16 percent less stress than teeth without keels when subjected to a 10lb-load. Researchers also noted that adding the keel increases the mass of the tooth by only 4 percent. Credit Jacobs School of Engineering/UC San Diego Usage Restrictions Please credit Jacobs School of Engineering/UC San Diego 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.