Entire 525 Million-Year-Old Hemichordate (image) University of Leicester Caption This is the entire 525 million-year-old hemichordate. Credit Credit: Professor Derek Siveter, Oxford University Usage Restrictions Use only with credit. 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.