How microorganisms r useful 4 us?

There are so many different kinds of microorganisms out there it would be hard to list them all...phytoplanktons produce 70% of the world's oxygen...forms of diatoms are used as pool cleaners...a bacteria that lives on your face eats the dead dry skin...zooplanktons provide food for schooling fish that we eat...mushrooms provide a food (yes mushrooms are microorganisms)...and so much more.