An amoeba, often called an amoeboid, is a type of cell or unicellular organism which has the ability to alter its shape, primarily by extending and retracting 'pseudopods'. Amoebae do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeba is a unicellular organism that has the ability to change its shape. They are usually found in water bodies such as ponds, lakes and slow-moving rivers. Sometimes, these unicellular organisms can also make their way inside the human body & can cause various illnesses.