The first living things on earth were microorganisms. They evolved around 3.8 billion years ago! Today scientists think that microbes make up Microorganisms, or microbes, are organisms that are very, very tiny. They are studied under micropscopes. Today, microorganisms are living everywhere- in our oceans, on and in land, in all of earth’s biomes, even in us! They are very very tiny and can only be seen under microscopes. There are four main types of microbes- bacteria, and viruses. Bacteria are one-celled microbes Please share resources, activities, and links by sharing them with Technically a microorganism or microbe is an organism that is microscopic. The study of microorganisms is called microbiology. Microorganisms can be bacteria, fungi, archaea, or protists. The term microorganisms does not include viruses and prions, which are generally classified as non-living.


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