Diatom (IMAGE) University of California - San Diego Caption Diatoms like these are a common and diverse group of phyoplankton in aquatic environments. They usually produce superoxide in their watery surroundings for reasons that have remained mysterious until now. Credit Julia Diaz 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.