What are called micro organisms​

A microorganism, or microbe, is a microscopic organism, which may exist in its single-celled form or a colony of cells. ... Microorganisms include all unicellular organisms and so are extremely diverse. Of the three domains of life identified by Carl Woese, all of the Archaea and Bacteria are microorganisms.

if you know your abc's you should be able to get your answer or just use google