ra·di·o·lar·i·an 
(rā′dē-ō-lârē-ən)
(rā′dē-ō-lârē-ən)n.
Any of various marine protozoans of the order (or phylum) Radiolaria, having rigid siliceous skeletons and spicules.
[From New Latin Radiolāria, order name, from Late Latin radiolus, diminutive of Latin radius, ray, spoke (in reference to their spicules); see RAY1.]
radiolarian