Radiolarian protozoan. Darkfield illuminated light micrograph of the fossilised internal siliceous (silicon) skeleton of a Radiolarian protozoan. Radiolarians are amoeboid protozoa that produce intricate mineral skeletons. They are found as zooplankton throughout the ocean, and their skeletal remains cover large portions of the ocean bottom as radiolarian ooze. This specimen was collected from Barbados. Magnification: x71, when printed 10 cm wide.