The Kessok were a civilization of lifeforms native to the Alpha or Beta Quadrant. The Kessok were somewhat unusual compared to other known humanoid cultures for both chemical and societal reasons—they were silicon-based and did not have notable genders.
In 2378, the Cardassians discovered the species, and made first contact with overtures intended to give the impression that they were protecting the Kessok. The Kessok, under Cardassian manipulation, attacked several starships, including the USS Berkeley at the Vesuvi Dust Cloud and the IKV Jonka in the Belaruz star system. The Federation first noted the Kessok's movements based on information gathered by the USS Sovereign in the Nepenthe system. In the Belaruz system, a Kessok named Neb-Lus told the Sovereign crew the Kessok's story and joined the effort to stop the Cardassian plot at the Omega Draconis system, providing the chance for a proper first contact with Starfleet. (ST video game: Bridge Commander)