An amoeba (; rarely spelled amœba, US English commonly ameba; plural am(o)ebas or am(o)ebae ), often called amoeboid, is a type of cell or organism which has the ability to alter its shape, primarily by extending and retracting pseudopods. Amoebas do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals.