Without a microscope, you cannot observe a microorganism. Additionally, germs and other microorganisms found in tainted food cannot be tasted or odored. However, you can smell the stench of sweat being broken down by germs. Fungal infections in the toenails also emit an odour.
Only a few fungi and algae are microorganisms, whereas all bacteria and archaea are. Some animals are minuscule, including practically all protozoa and rotifers. Small organisms inhabit soil, the atmosphere, the ocean floor, and the inside of rocks.
In order to recycle nutrients in ecosystems, microorganisms assist in decomposition. Microbes in the air may have an impact on precipitation and weather. In the nitrogen cycle, others are engaged.