Although this ship did exist in the game at one time (2001), it was replaced by the newer, chunkier and vertically-oriented Vaygr mothership-class vessels. It is seen in the E3 2001 flyer and trailer that were kept secret at the time.

It is -- or at least was -- a mothership-sized command carrier. One of the concept arts labels it as "Agamemnon". In another it's labeled a "Supercarrier."

An upsized, wrecked version appears in the Karos Graveyard in Mission 08. It is referred to in the game files as "Big Red."