Mycrozymas are very tiny. But they can grow and change into larger and larger forms.

Its impossible to see them with a normal bright field scope for two reasons, one the white light is so intense that it kills them and two the white light's wavelength is too long and by the laws of physics limits the reflectivity ability fo the light to 200 nm.


A red blood cell is about 200 nanometer and anything smaller then that is essentially invisible in a normal microscope.


The only way to look at a living blood sample is with a Dark Field Microscope that uses light with a shorter wave length. That way with the same magnification you can look at things that are smaller then 20 nanometers.

And because you are looking at them in shadow they are not killed by the light.