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Microorganisms
There are 3 main types of micro-organism, fungi, bacteria and viruses. The most useful is perhaps fungi, the most well known being penicillin which is basically mould! And of course there are many types of harmless bacteria (as well as the more nasty types)which are involved in keeping us healthy.
First answer by Zilly. Last edit by Zilly. Contributor trust: 112 [recommend contributor]. Question popularity: 28 [recommend question]





