Matoran Universe

The Matoran Universe was a system of "gigantic domes" inside Mata Nui's "body" in Aqua Magna. It was made by the Great Beings and watched over by the Great Spirit Mata Nui himself before Teridax succeeded in his Plan to control the universe.

History
The Matoran Universe was created by the Great Beings over 100.000 years ago, who set Tren Krom to watch over it. Then Mata Nui was born, and he was set to watch over the Universe, while Tren Krom was exiled to a barren island and fused to a rock in a cave. Also, the Brotherhood of Makuta and the Hand of Artakha were created, the first one to create Rahi, and the second to enforce order in the Universe. But the Hand didn't last very long, and was replaced by the Toa. The Order of Mata Nui was also created around that time, to carry out Mata Nui's will. The League of the Six Kingdoms once tried to overthrow Mata Nui and sieze control of the Universe, but were defeated by the Brotherhood, a member of which got an idea how Mata Nui could really be overthrown. This Makuta, Teridax, soon took control of the Brotherhood and devised a plan to control the Universe. About 300 years before the Great Cataclysm, the Brotherhood infected Mata Nui with a virus that gradually put him asleep. When Mata Nui finally fell asleep, a great earthquake shook the Universe, in an event known as the Great Cataclysm. After the Great Cataclysm, most of islands of the Matoran Universe shot to the surface. Mata Nui was also dying and was close to death when the Matoran returned to Metru Nui. The Toa Inika were sent to Voya Nui to recover the Kanohi Ignika, and heal Mata Nui. But they were too late and Mata Nui died. The whole Universe would have been flooded in about three days, but Matoro sacrificed his life to revive Mata Nui. But the Life in the Universe was still in danger, because the the brotherhood found a way into the Universe Core, and so a countdown was triggered in the Ignika, at the end of which it would drain the life of all beings in the Universe. The mask soon realised it was a threat to the Universe, and eventually sacrificed itself to fully awaken Mata Nui. When Mata Nui awoke, Makuta Teridax shoved Mata Nui's spirit out of his body and took control of it himself, succesfully gaining control of the Matoran Universe. Mata Nui's spirit was banished to the Ignika, which was itself banished from the Matoran Universe.