Actinosphaerium protozoan. Darkfield illuminated polarised light micrograph of an Actinosphaerium sp. heliozoa protozoan. This single-celled freshwater organism has many pseudopodia radiating outwards from its cell body that are used for capturing prey. A peripheral layer of large vacuoles assist in floatation. Magnification: x200 when printed at 10 centimetres wide.