Ammonia is a waste product excreted by aquatic animals, as well as some other organisms, including Amoeba.

• Amoeba's main waste products are ammonia and carbon dioxide. It excretes waste through diffusion, which is the movement of molecules from a higher concentration to a lower concentration.

• Other organisms excrete nitrogenous wastes in different forms, including:

• Birds and lizards: Excrete nitrogenous wastes as uric acid 
• Humans: Excrete urea 
• Reptiles and many terrestrial invertebrates: Produce uric acid