Amoebas are composed of just one cell. They are protozoans with no fixed shape. Most have no hard parts and look like blobs of jelly. However, some amoebas do build shells.
Amoebas move by making part of its body move in the direction it wants to travel. Then slowly, the rest of the cell follows. In order to eat, an Amoeba flows around other microorganisms and then engulfs them. To reproduce, the Amoeba splits itself into two cells.