MICROORGANISMS A microorganism is a living being that is too small for the human eye to see. Bacteria, fungi, archaea, protozoa, and minute animals, such as the dust mite, are examples of microorganisms. Almost ubiquitously on earth, microorganisms exist where there is freshwater or even a slight amount of moisture, from hot springs on the ocean bottom, deep inside rocks inside the surface of the earth, on human skin, and, inside a sponge used to wash dishes. For nutrient recovery in habitats, certain microorganisms are important because they act as decomposers, while others living in nodules on the roots of certain plants turn nitrogen from the environment into a plant-usable shape. Under good growing conditions, micro-organisms reproduce quickly, often leading to the gain of the greater host plant or animal organism and living in a balanced dynamic equilibrium with other micro-organisms and the host organism. However, at times, pathogenic microbes can invade l