Fresh water protist (protozoan) Amoeba proteus feeding on small ciliates. Amoebas (amebas) are well known for their variable shapes (the word amoeba comes from the Greek for "change"). They move by extending cytoplasmic feet or pseudopodia (single: pseudopod, from the Greek for "false foot") -amoeboid movement. Amoebas are reasonably amorphous but they often have a discernable rear end (uroid), shown at upper left. Amoebas are unicellular organisms and they reproduce by binary fission.