The Mnemeion (a.k.a. the "Graveyard" or "Cemetery") is an ancient mobile fortress starship made by the Innovation Empire to defend themselves from Beasts. The Zail Family ordered its creation from a deactivated Blue Flower during the Great War. There are no known records of Mnemeion's actual field performance but this is most likely due to the ravages of the war then.
The Mnemeion was discovered already inactive and lacking its core in the 7th Ground Zero on Vine. It was then declared as a lost technology artifact. Research on the site confirmed that the Vine Ground Zero was a derelict shipyard of the Innovation Empire.
In CC 400, EX-Type Zero Rabbit attacked the 7th Ground Zero during the First Battle of Tobal presumably with the intent of destroying the ancient superweapon. Knight Order prioritized the recovery of the uninhabited Vine over the inhabited planet Tobal due to the perceived breakthrough importance of Mnemeion in the Human-Beast conflict. Unfortunately, despite multiple studies, neither the Knight Order nor AE had the proper technological capacity to reactivate Mnemeion. As such, the 7th Ground Zero was no longer deemed critically important after the First Battle of Tobal - the people of Tobal suffered for virtually nothing.
It was further studied but ultimately left in its preserved state until the arrival of Lieutenant General Tinie in CC 431 who attempted to reactivate it with the core of a Blue Flower that fell on Tobal. Tinie used another Innovation Empire lost technology, the "God's Pillars", to act as a controller to the core and Mnemeion. The plan was successful but EX-Type Two Chatterbox killed and replaced Tinie as Mnemeion's commander. Mnemeion was then used extensively by the Beasts in the Third Battle of Tobal to resume Queen E-34's war to exterminate humanity.
Chatterbox and Hyperion Repair used Mnemeion as their main base for attacking Tobal. Chatterbox had the mobile fortress bombard the planet's surface with its particle beam cannons. The Tobal Union, under Robert Nelson's direct, command attempted to strike the mobile fortress with the combined forces of their fleet and Tinie's AE fleet. Nelson also had the Golden Ring Orbital Cannon prepare to fire on Mnemeion. However Chatterbox hacked the cannon instead and had it incorporated into the fortress as an additional armament. Golden Ring was then used to destroy the entire Tinie AE fleet before aiming again at Tobal. The TU fleet launched a desperate suicide charge towards Mnemeion but it only managed to destroy Golden Ring.
The TU, enlisting the help of Sion Zail and Van Nelson, launched another offensive operation to slay the two EX-Types and neutralize the mobile fortress. Sion engaged Hyperion while Van fought Chatterbox. Hyperion, being cornered by Sion's skills, began injecting Mysteltein to his core to turn into the planet-eroding World Tree. Unfortunately, he was still slayed by Sion. Chatterbox then recovered the concentrated core essence of Mysteltein/World Tree and had it merged with the core of Mnemeion. The mobile fortress then turned into the new foundation for the World Tree and began producing flowers that distorted/eroded everything it touched. Sion and Van, assisted by TU, made a last push attempt to stop the carnage. Finally, the two slayed Chatterbox after another exhausting fight. Van and Sion then made their way to destroy the core chamber of Mnemeion where the seed of the World Tree was planted. The mobile fortress then crashed to the surface of Tobal signalling the end of the battle.
Sion commanded the Mnemeion to reactivate again when Van was assassinated by grieving TU soldiers in the middle of the Tobal Civil War. She boarded the mobile fortress with the body of Van but the remaining Beasts within Mnemeion were also awoken and they started attacking. By asserting her Zail code, Sion then instructed Mnemeion to warp at the rear of the intervening Alternative League fleet specifically so that Supreme Commander Dry Leonhard would be forced to battle Mnemeion and the Beasts. Dry, acknowledging the ploy, still complied and burned all Beasts down along with huge swaths of the fortress. The two then made a secret arrangement that involved exchanging Sion's code for something. Sion then last instructed the fortress to warp into an isolated but serene unknown planet in the distant unexplored regions of the universe.
Many decades later, the unknown planet is discovered by an elderly Mio, now known as a leading expert in planetary research and terraforming. She found the wreckage of the inactive Mnemeion half-submerged in an ocean. It can be surmised that Sion was able to fully deactivate the core as there were no traces of erosion on the tranquil planet. There were evidences of a person living in the planet but Professor Mio corrects her understudy as she believes there were two people. Mio then names her discovery as Planet "Sion".
The Mnemeion possess fearsome weaponry such as numerous large and small particle beam cannons, concentrated on its underbelly and the tail which can unleash a devastating attack on a given target. The Mnemeion also possesses the ability to manipulate gravity much like the members of the Zail Family of the Innovation Empire that commissioned for its construction. Mnemeion's gravity device is greatly enhanced in terms of range and scale as it was able to wipe off the entire Karin Island in Tobal.
During the Third Battle of Tobal, Chatterbox hacked into the Golden Ring Orbital Cannon and merged it with the Mnemeion. The floating fortress' armaments were then shortly supplemented by this added firepower.
Mnemeion naturally possess thick crust-like armor which it inherited from its origins as a reversed-engineered Blue Flower. Complementing this, the fortress is also equipped with an impressive array of powerful barrier generators.
The Mnemeion appears to be able to operate both within atmospheric conditions and outer space. While the ancient mobile fortress has a slow cruising speed due to its massive size, it can use instantaneous independent warp similar to Black Hole Engines to travel to its destination.
As a fortress, it has facilities to maintain a garrison and other related amenities. The docking bay of Mnemeion is large enough for several Beast Mecha to fit inside.