An assemblage of eukaryotic protists comprising the testate (shelled) amoebas. Although constructed chiefly on the basis of molecular systematics, the group features threadlike (filose) pseudopodia. Members include the radially symmetrical heliozoans (sun animalcules); the radiolarians with their intricately sculpted siliceous skeletons; the foraminiferans, characterized by pore-covered shells made of sand or organic materials; and the cercozoans, such as the euglyphid amoebas. Some authorities now tentatively place the rhizaria in a supergroup with the chromalveolates.
Subjects: Biological Sciences.