n. The smallest of the faunal size divisions, including mainly microorganisms but also sometimes applied to the tiniest species of animal groups such as ticks, insects, etc.
The Century Dictionary and Cyclopedia
n. A fauna in which all the animals are of minute or diminutive size; a congeries of microscopic animals, or sometimes a depauperated fauna.
Word Usage
"If you try ferments at home, you may find some interesting microfauna try to crash the party."