Vessels of Anima, are mysterious artifacts, shaped like enormous human spines, that were uncovered along with the Zohar during the excavation at Lake Turkana in 20XX AD. They are introduced in Xenosaga Episode II as being primary components of the E.S. series of battle robots, where they heighten the response rate between the E.S. and the pilots. At the start menu of Episode II, E.S. Asher can be seen being assembled and in mid-game Zebulun, technicians assemble various components around the spine shaped Vessel of Anima in an anti-gravity chamber. Technically, a mech becomes an E.S. only when a Vessel of Anima is equipped. Despite their origin and true purpose not being explained, the Anima Relics feature as a prominent symbol throughout Episode II, appearing in the game's logo and in the title 'attract' screen, where one is seen being fused with the E.S. Asher. They are first mentioned in a conversation between U-TIC and Ormus officials Pellegri and Margulis, where we learn the bulk of the known information on the relics.
The actual function of the Vessel of Anima, at least as used within the game, is as a modified power source for mobile weapons of the A.M.W.S. type. While both A.M.W.S. and A.G.W.S. are generally powered by a Transmit Generator which draws power from a local power source, the E.S. units and their associated Anima Relics draw power from the Zohar. Because of this fact, the E.S. are capable of much greater power and speed than an average A.M.W.S. and have the enormous advantage of being able to operate basically anywhere in the known universe, rather than simply within the area of influence of a generator. In Episode III the player has the option to activate the Vessels to enter a stage of decreased energy usage and to employ special attacks. The Anima Relics also have other functions, similar to the Zohar, beyond as a simple power source, although the player does not have the ability to access any such functions.
It is revealed in Episode III that chaos is actually the Anima. The Anima power was divided into twelve relics (the Vessels of Anima) by none other than Mary Magdalene on Lost Jerusalem in ancient times. The Vessels of Anima are referred to as the "body of God" by Wilhelm and the "power of God" by the database.
A related set of Vessels of Anima also appear in Xenogears and greatly influenced the mechs/Gears, presenting extraordinary strength compared to the average Gear. While A.M.W.S mechs turn into E.S. upon installation, the gears in Xenogears morph into the infamous Omnigears when exposed to the power of Anima.
While the Gazel Ministry are the Animus (the male component), Anima is the female component. It is because of this fact that they do wish to take control of the Land Dweller's bodies that have been aligned with the Anima to become one with them and return to the -Persona- (Deus).
Xenogears Anima Relics
Anima Relics aligned 500 years prior to the events in Xenogears:
Naphtali was aligned with Grahf - Gear: Alpha Weltall
The other four anima relics called Reuben, Simeon, Levi and Issachar have unknown hosts, though it is speculated that they were aligned with gears used by the Gazel Ministry before they became the SOL-9000 Computer. Had the game been finished, two of these relics probably would have been aligned with Crescens and Seibzehn and the other two would probably been used by the enemy or by your allies, but would not be able to be used by the party,