Histamine Staining of Purple Sea Urchin (IMAGE) BMC (BioMed Central) Caption This image shows extensive histamine containing cells in metamorphic all competent sea urchin larvae (Strongylocentrotus purpuratus). Credit Andreas Heyland 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.