|Native Species:||Sargon's species (extinct)|
Arret had been an inhabited planet in the ancient past. It was the homeworld of a warp capable humanoid species that went on to colonize the Milky Way Galaxy. The planet was located hundreds of light years past the limits of Federation exploration in 2268. (TOS: "Return to Tomorrow")
Originally Earth-like, though much older, the atmosphere of Arret was ripped away by a cataclysmic war fought half a million years before the USS Enterprise arrived in orbit. By the 23rd century, its surface was devoid of life.
Eleven survivors of that great war had created a shelter 112.37 miles below the surface. This vault was constructed of a material harder and stronger than anything Commander Spock had measured at that time; its atmosphere was "a fraction richer in oxygen than usual".
Originally humanoid, the eleven surviving members of Sargon's species placed the essence of their minds into spheroid receptacles. In 2268, only two spheres besides Sargon's still contained a living mind: that of Thalassa, Sargon's wife, among the five spheres kept on the lower tier, and that of Henoch, a member of the conflict's "other side", on the upper. (TOS: "Return to Tomorrow")