Varied Structure for Added Strength (IMAGE) University of Copenhagen - Faculty of Science Caption A heavily enlarged 3-D print of the sea urchin shell in cross section reveals the secret to the immense strength of the calcium shell of the sea creature. Dirk Müter, Assistant Professor at the Department of Chemistry, University of Copenhagen, discovered that hundreds and thousands of tiny struts criss-cross the material making the sea urchin shell more air than calcium. Credit Jes Andersen/ University of Copenhagen. 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.