|Former Residents||Toa Mata|
The Codrex was a massive sphere located deep in the swamp of Karda Nui, built by the Great Beings. It was the structure in which the Toa Mata entered their Toa Canisters to await the day they were needed, and was where they had to go to reawaken Mata Nui. The Codrex was protected by an energy field that not even the power of a Toa Nuva or a Makuta could penetrate. The only way to enter was to place the 6 Keystones into a special niche in the field.
When the Toa Nuva, Takanuva, and "Toa" Ignika entered the Codrex, Makuta Antroz snuck in before the energy field would reenable itself. Lewa, Pohatu, and Kopaka found the T-Series vehicles, though before Kopaka could claim the Jetrax, Antroz hijacked it.
"Toa" Ignika later decided to sacrifice his body to reactivate the ancient systems of the Codrex and the Energy Storms.
Unlike other locals in Karda Nui, the Codrex was unable to be destroyed by the Energy Storms.