Light micrograph (LM) of a shelled amoeba protozoan, Arcella sp., surrounded by organic debris. Arcella is a testacean amoeba. The shell of this species forms a flattened dome with a hole in the middle of the underside. The shell is made of a brown or straw-colored protein. The amoeba can feed by extending its pseudopodia out of the opening in the shell to capture tiny organisms. The Arcella genus is common in fresh-water ponds. Magnification x83 at 35mm.