Microscopic Pictures of Foraminifers (IMAGE) NIOZ Royal Netherlands Institute for Sea Research Caption Microscopic pictures of individual foraminifers. Left: A foraminifer with a shell containing four chambers of which one is empty. Also note the spines. Right: Picture of the interior of a foraminifer. The green colour is caused by seawater with an indicator showing that the acidity has changed. The actual size of the foraminifer is about 0.25 millimeter. Credit Dr. Lennart de Nooijer (NIOZ) 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.