Ocean Life & Ecosystems. Ocean Explorer: Islands in the Streams 2001: Giant red brittle star. Sea urchin spine structure inspires idea for concrete. 15 February 2012Last updated at 01:57 By Jason Palmer Science and technology reporter, BBC News The spines do not break cleanly, suggesting they are not made solely of single crystals The precise structure of sea urchins' strong spines has been unravelled - and the find may contribute to stronger concrete in the future. The tough spines are known to be made of calcium carbonate, which has a number of naturally occurring forms, some more brittle than others.
X-ray studies now show they are built from "bricks" of the crystal calcite, with a non-crystalline "mortar". The results are reported in Proceedings of the National Academy of Sciences. The spines serve as a defence against predators, hard and at the same time shock-absorbing. The urchins' strong spines serve as a defence against predators But efforts to understand exactly how they are put together have yielded confusing results. He told BBC News: "It still hasn't been resolved. " Basic recipe. NOAA - National Oceanic and Atmospheric Administration.