A microorganism is an organism too small to examine in detail with the unaided eye. Bacteria and many fungi are familiar examples.
What this means at your property
Microscopic does not mean that every organism is harmful or that every surface requires the same treatment. A property assessment should connect a finding to the actual source, materials and purpose of the work.
Can a visual inspection identify the organism?
A visual inspection can record a condition but generally cannot identify a microscopic organism. Ask whether identification is necessary for the project and what a proposed test would establish before treating a generic label as a diagnosis.