Members of the phylum Rhizopoda, amoebae and their relatives are all unicellular.Consisting of a nucleus, cytoplasm as well as food and contractile vacuoles, amoebae inhabit both fresh water and marine environments and are commonly found in coastal rockpools. Amoebae do not have a fixed shape. Instead, they constantly change their body shape by creating cellular extensions known as pseudopodia or cytoplasmic extensions which aid in feeding and locomotion pseudopodia may protrude from anywhere on the amoeba's cell surface.