Radiolarians are free floating marine organisms. Their protoplasm is differentiated into intra and extra capsular type. Pseudopodia arise from extra capsular type and help in movement. They may be axopodia or filopodia type. Intra capsular type has nuclei and vacuoles. Binary fission and spore formation are different modes of reproduction. They have oozing material known as Radiolarian ooze. This act as a abrasive and filtering agent like diatomaceous earth.