any of various marine protozoans constituting the order Radiolaria, typically having a siliceous shell and stiff radiating cytoplasmic projections: phylum Actinopoda (actinopods)
Word origin
C19: from New Latin Radiolaria, from Late Latin radiolus little sunbeam, from Latin radius ray, radius
radiolarian in American English
(ˌreɪdioʊˈlɛriən)
noun
any of several classes of one-celled deep-sea protozoans with long, slender pseudopodia and a spiny, or solid but perforated, skeleton of silica
Word origin
< ModL Radiolaria < radiolus, dim. of L radius, ray (see radius): from the radiating pseudopodia