The term 'Tiny Shape-Shifter' can be summarized by the crossword solution 'AMOEBA' (6 letters). An AMOEBA is a single-celled organism that is capable of changing its shape. It is found in many different environments, including freshwater, soil, and even the human body. Amoebas are considered to be among the simplest forms of life, and they are able to move around by extending and retracting their pseudopods.