Nassellaria radiolarian. Coloured scanning electron micrograph (SEM) of the shell of a Nassellaria sp. radiolarian. Radiolaria are single-celled protozoans that are found in marine plankton. This radiolarian has a silicate skeleton with pores through which needle-like pseudopodia protrude . These 'little feet' are used to carry out a process called 'cytoplasmic-streaming' : a means of locomotion and to distribute nutrients and oxygen. “Rhizaria.” Boundless Biology. Boundless, 27 Jun. 2014.