The term 'single-celled creature' refers to a type of organism that consists of only one cell. Three examples of single-celled creatures are AMOEBA (6 letters), MONAD (5 letters) and ameba (5 letters). AMOEBA are microscopic, unicellular organisms that move by extending and retracting pseudopods. Monads are also microscopic, unicellular organisms that are found in freshwater environments. Ameba are single-celled protozoa that move by extending and retracting pseudopods. All three of these single-celled creatures are classified as protists, which are eukaryotic organisms that are not animals, plants or fungi.