Know how to use "fewer" and "less"? Find out.
Any of various protozoans of the order Arcellinida (or Testacida) that are encased in a shell. Testaceans are rhizopods and are related to amoebas. Their shell usually has one chamber and may be secreted by the organism as a chitinous or siliceous covering, or may be glued together out of sand particles.