Ameba

Ameba, or amoeba, microscopic, one-celled organism that lives in moist earth, water, and parasitically in the bodies of animals. The ameba is a shapeless cell of jellylike material (protoplasm) encased in a thin membrane. It constantly changes shape by forming temporary projections called pseudopods (false feet) used for feeding and locomotion. The ameba reproduces by fission (splitting). Amebas are harmless to people, except for a type that inflames the lining of the large intestine, causing a disease called amebic dysentery.