Places and their Geography (Bionicle Supplement)
From D&D Wiki
A moon of Bara Magna that is completely covered in ocean. The Matoran Universe resides here in a deep slumber, waiting to be reactivated so that it may complete its maiden voyage. Dispite most of Matoran history happening on this moon, not much is known about it aside from what's been learned from the waters explored around the island.
The Matoran Universe (Mata Nui)
The various lands and cities below the island of Mata Nui and the original home of the Matoran. Metru Nui was somewhat of a utopia for architecture and innovative technology.
Metru Nui is devided up into 6 regions, 1 for each of the primary elements (fire, water, earth, air, ice, and stone). A large colosseum stands in the intersecting region of all the aforementioned regions. Chutes with flowing liquid protodermis run throughout Metru Nui for shipping supplies long distances. As it is an island, it is surrounded with liquid.
Mata Nui (island)
The island of Mata Nui, named to honor the great spirit of the same name by the Matoran, became the new home of the Matoran once they escaped the Great Cataclysm. The island is no where near the level of sophistication of Metru Nui, and there are many unrestrained beasts roaming freely upon its soil. Matoran have learned to live as islanders (fishing, basket weaving, surfing) quite well in these harsh conditions.
Metru Nui's face is devided up into 6 regions, 1 for each of the primary elements (fire, water, earth, air, ice, and stone). As it is an island, it is surrounded with liquid.
A harsh, barren wasteland known as home to the Agori, Galadatorians, Skrall, and several other species. As it is a planet, it is surrounded by space.
A moon of Bara Magna that is almost completely populated with plantlife.
Spherus Magna (Whole)
In the events of Mata Nui's return, the planet Bara Magna was reunited with its two moons, Bota and Aqua Magna, becoming whole again and forming Spherus Magna once more.