a single-celled aquatic animal which has a spherical amoebalike-body with a spiny skeleton of silica. Their skeletons can accumulate as a slimy deposit on the seabed 放射虫
Three classes of the phylum Actinopoda, kingdom Protista (formerly subclass or order Radiolaria) 辐足门3纲,原生动物界(原放射虫亚纲或放射虫目)