The tiny civilization are a small civilization that inhabit a small, distant planet. On their planet, Spaceman Spiff encounters first some lichens and mosses which turn out to be small trees and farmland. He then comes upon a very tiny city. During the encounter, Spiff reflects on how the standard human measurement is no way to live by. The city is apparently threatened by the Doofus Ignoramus that appears.
In real life, these aliens are just ants and their city is an anthill.