Sea Urchins (IMAGE) American Museum of Natural History Caption Sea urchins, a small sampling shown here, originated about 265 million years ago, and have diversified through episodic bursts over time. Credit © AMNH Usage Restrictions Can be used with appropriate credit 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.