Microscopic civilization
A tiny Dyson sphere built by a microscopic civilization, as imagined by Sam Rutherford
A microscopic civilization was any civilization that consisted of sentient microbes.
In 2381, when Ensign Sam Rutherford was obsessing over how Lieutenant Shaxs came back from the dead, he imagined several possibilities that could have brought him back.
One of the things that he imagined was that a microscopic civilization brought him back to harness the power of his body with a tiny Dyson sphere. (LD: "We'll Always Have Tom Paris")
The sentient nanites settled on Kavis Alpha IV would conceivably qualify as a microscopic civilization.