The Gw'oth (singular: Gw'o) were first encountered in Larry Niven and Edward M. Lerner's? collaborative Fleet of Worlds series of novels (a subset of Niven's Known Space future history).

The Gw'oth resemble starfish and inhabit the ocean under the ice of their home world, the moon Jm'ho?. When linked together — using a vestigial talent that few Gw'oth retain — they can form a powerful biological computer. One such instance is named Ol't'ro. Ol't'ro is composed of 16 Gw'oth individuals that link themselves together into a 'meld' or ensemble mind called a Gw'otesht. Ol't'ro is featured prominently throughout the Fleet of Worlds series.

Ol't'ro's ultimate fate is unknown after the Fate of Worlds book in the series. Whether Ol't'ro died in the explosion of planets or somehow escaped is left unanswered. Ol't'ro had just solved the mystery of Type II hyperspatial travel so it is possible but unknown that the Gw'otesht managed to escape in that fashion.

Evolved to sentience from colonies of carnivorous tubeworms living beneath the ocean of an ice moon similar to Europa, the Gw'oth broke through the ice and first experimented with fire only two generations previous to mastering nuclear fission. The Gw'oth continue to advance rapidly without need for trial and error learning. They know nothing of other intelligent beings in the universe until first encountering Humans and Pierson's Puppeteers in Fleet of Worlds. Though superficially similar to the Jotoki, they are unrelated.

Sources: Fleet of Worlds, Juggler of Worlds, Destroyer of Worlds, Betrayer of Worlds, Fate of Worlds

Other sites: Wikipedia, Larry Niven Wikia,