Ostracoda (IMAGE) European Synchrotron Radiation Facility Caption Mussel shrimps (Ostracoda) are small, bivalved crustaceans living in marine and freshwater environments. Their calcified carapace is readily fossilized, resulting in a fossil record stretching back almost 500 million years. This green freshwater species Eucypris virens prefers temporary pools (left in lateral view, right in ventral view, total body length approx. 1.8 mm). Credit Renate Matzke-Karasz 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.