Step-by-step explanation:
Amoeba is a single eukaryotic organism which has no definite shape. It moves with the help of pseudopodia. In order to obtain food, amoeba uses a process called phagoctyosis.
It can easily divide itself into two or more daughter cells. Thus, we can conclude that unicellular organism which moves and engulfs food by changing the shape of its body is amoeba.