Microorganisms are tint living things! Some examples of microorganisms are viruses, bacteria, fungi, and protozoa! Microorganisms can only be seen using a high-power microscope. These microorganisms can live in the most extreme places like in the air, in deserts, and inside of soil! How can there be billions of microorganisms in just a teaspoon of soil?
It is all because that soil contains so many bacteria, fungi, protozoa, and sometimes viruses! Soil is full of nutrients, old material, and living things! The microorganisms in the soil do all sorts of things, like decomposing material and feeding ecosystems. These microorganisms fill up the soil and are so tiny, which means that there is a lot of them packed together. That is why in a teaspoon of soil, there are more microorganisms than there are poeple on planet Earth!