MorningLightMountain is a collective of Prime immotiles, and is currently the sole remaining Prime hive-mind known to exist. It launched a genocidal war against the Commonwealth (i.e., humans), described in Pandora's Star and Judas Unchained.
The identifier "MorningLightMountain" signifies the collective's place of origin, a mountain peak located in a valley that is only illuminated by the morning sunlight. It later became the dominant Prime collective throughout most of the species' history, and ultimately destroyed the other immotile collectives in a bid for total dominance. It used wormhole technology, obtained from the human Dudley Bose, and nuclear warheads to destroy the other immotiles. By opening a wormhole and dropping a warhead through, MorningLightMountain emerged as the only Prime life in its solar system, Dyson Alpha.
The Starflyer, a secretive alien which covertly influenced humanity into starting a war with the Primes, was in fact an AlienPrime offshoot of MorningLightMountain, MorningLightMountain #17,735.