Matoran Universe

The Matoran Universe was a system of "gigantic domes" inside the Great Spirit Robot 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 as a giant mechanical being, 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. Mata Nui's mission was to learn about the external Universe and then return to the Bionicle Solar system and reunite Spherus Magna. 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. After Teridax finally gained control over the Universe he traveled to Bara Magna to fight and destroy Mata Nui. After battleing him in an older prototype robot, Teridax was finally killed by a small piece of Aqua Magna, which had broken off during it's flight through space, as it approached. The Matoran Universe fell on the now recreated Spherus Magna. The inhabitants escaped and made new lives for themselves on their new home.

Known/Popular Islands and Locations
The Matoran Universe is comprised of various domes; massive, individual caves separated by gates with oceans and islands of their own. Also, during the Great Spirit Robot's stay on Aqua Magna, some new locations were made on Aqua Magna's surface:

On Aqua Magna
Mata Nui (island): An island that was created on Aqua Magna's surface by a malfunction in Mata Nui's camaflouge system when he crashed landed during the Great Cataclysm. Due to a leak of Energized Protodermis, the island was covered in plant life. After the Matoran population of Metru Nui was placed into Matoran Spheres, the Toa Metru brought them to live there (who gave up their Toa power to be Turaga and to release the Matoan). Makuta Teridax also went with them, and started to torment the Matoran with mind controlled Rahi. He also released the Bohrok swarms on Mata Nui in order to recuperate. Eventually, the Matoran went back to Metru Nui, and the Toa Nuva released the Bohrok swarms as part of a list of necessary things to do in order to awaken the Great Spirit. When Mata Nui awakened (with Teridax's mind), the island, which had been completely made barren, was destroyed by the Great Spirit Robot's head rising up and shattering the island.

Voya Nui: An island that was created during the Great Cataclysm. It was originally part of the Southern Continent, and it was the area where the Kanohi Ignika was kept. Many caves exist beneath the island. During the Great Cataclysm, it rocketed out of the universe, and was floating on Aqua Magna. Molten protodermis created a new but unstable landmass on the shore, and a city was settled on it called Mahri Nui.

Mahri Nui:  

Inside the Matoran Universe
Metru Nui:

Karzahni:

Zakaz:

Xia:

Stelt:

Northern Continent:

Artakha:

Tren Krom's Island:

Destral:

Odina:

Nynrah:

Visorak (island):

Daxia:

Southern Continent:

Karda Nui:

The Pit:

Artidax:

Keetongu's Island:

Isle of Energized Protodermis Entity:

Southern Islands: