The Scintilla were a civilization of intelligent microbes. They lived in colonies at the bottom of deep lakes on a class M planet.
In the mid-23rd century, the Federation starship USS Farragut launched its shuttlecraft McAuliffe on a survey mission to the planet's northern highlands. The crew observed a faint blue glow coming from the lakes which was emanated by the Scintilla.
Years later, a translation breakthrough led to communications being established between the Scintilla and the Federation. (ST reference: Ships of the Line)