Onu-Metru
The deep archive-city that made mining and historical records preservation the beating heart of Metru Nui.

Onu-MetruMetruIn the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it. was an entire civilization built on darkness and duty. Thousands of Onu-MatoranOnu-MatoranEarth-wielding Matoran of the deep who adapted to darkness and built the Matoran Universe's defensive cavalry. spent their days in the deep mines and tunnels beneath Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive., extracting the resources the city needed to survive. The district's beating heart was the Archives, a sprawling complex where historical records and knowledge were preserved in the cold earth. WhenuaWhenuaToa Metru of Earth and later Turaga of Onu-Koro, formerly an Onu-Metru archivist whose career in the Archives shaped his role across the rescue of Metru Nui and the long residency on Mata Nui., the Toa MetruMetruIn the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it. of Earth, guarded this place as both protector and steward. But Onu-MetruMetruIn the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it. wasn't quiet or isolated. It was a major player in the city's politics, its economy, and its conflicts.
The Deep City#
The district's entire identity was tied to earth and stone. Onu-MatoranOnu-MatoranEarth-wielding Matoran of the deep who adapted to darkness and built the Matoran Universe's defensive cavalry. miners descended into tunnels that stretched for miles, extracting protodermis, metals, and other resources needed to keep Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive. running. These weren't shallow pits. The tunnels went deep, twisting into darkness where few ventured willingly. In the later years, maintenance problems threatened sections of the tunnels. When NuparuNuparuAn Onu-Matoran engineer from Metru Nui who built the Boxor and rose to become a Toa of Earth despite no warrior destiny. discovered a catastrophic leak in the Maintenance Tunnels during the time of the Toa MetruMetruIn the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it., it signaled something far more serious was unfolding, as per BIONICLEBIONICLE: Matoran AdventuresA 2002 GBA platformer where you play as one of six Matoran fighting Bohrok across Mata Nui's islands. Adventures 3: The DarknessDarknessThe Dark Hunter who shadows the Shadowed One himself, waiting for any sign of weakness so he can kill his leader and take his place. Below.
The Archives stood as Onu-MetruMetruIn the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it.'s other pillar. This wasn't a mere library. It was the repository of everything Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive.'s citizens needed to remember about their own history, culture, and past. WhenuaWhenuaToa Metru of Earth and later Turaga of Onu-Koro, formerly an Onu-Metru archivist whose career in the Archives shaped his role across the rescue of Metru Nui and the long residency on Mata Nui. and the other Toa searched its halls for the Great Disks, artifacts of immense power hidden throughout the city's districts, in BIONICLEBIONICLE: Matoran AdventuresA 2002 GBA platformer where you play as one of six Matoran fighting Bohrok across Mata Nui's islands. 2: Legends of Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive.. The Archives were so vast that WhenuaWhenuaToa Metru of Earth and later Turaga of Onu-Koro, formerly an Onu-Metru archivist whose career in the Archives shaped his role across the rescue of Metru Nui and the long residency on Mata Nui. and NujuNujuNuju served as a Ko-Metru seer, Toa Metru of Ice, and Turaga of Ko-Koro who spoke only in bird calls translated by Matoro. entered the wrong chamber while hunting for Onu-MetruMetruIn the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it.'s disk, stumbling into the territory of a Giant Mutant UssalUssalSix-legged crustacean Rahi domesticated across Metru Nui and Mata Nui for cargo, mining, and sport. Backbone of Matoran labor. Crab.
Politics and Conflict#
Onu-MetruMetruIn the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it. wasn't neutral ground. When tensions erupted between Ta-MetruTa-MetruThe fire district where Ta-Matoran perfected their craft and powered Metru Nui's industry for thousands of years. and Po-MetruPo-MetruMetru Nui's Stone District, home to carvers whose work defined the city and site of an ancient conflict that threatened to divide it. over trade disputes and territory, Onu-MetruMetruIn the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it. sided with the fire MatoranMatoranThe most abundant species in the Matoran Universe, chosen by Mata Nui to inhabit and maintain his cosmic body., according to The MutranMutranMutran is a Makuta of the Brotherhood of Makuta who serves as the Makuta of Voya Nui and is among the most prolific Rahi creators within the organization. Hailing from the Southern Islands, he wears the Great Shelek and commands the powers of Shadow and Silence alongside the full range of Kraata abilities, wielding a Shadow Blade, Shadow Spear, and Tridax Pod in combat. Chronicles serial. The decision dragged the district into larger conflicts. Ko-MatoranKo-MatoranIce Matoran who were quiet scholars and star-watchers, built to survive the frozen peaks of Ko-Wahi. tried to mediate but failed. Ga-MatoranGa-MatoranThe Water-element Matoran of Ga-Metru and Ga-Koro, a female Matoran type, who filled the schools of Metru Nui and crewed the boats of the Mata Nui coast. attempted neutrality and watched their efforts collapse. Every district took a stance, and Onu-MetruMetruIn the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it.'s choice mattered.
The RorzakhRorzakhThe Vahki model assigned to Onu-Metru, the Rorzakh were utterly relentless and carried Staffs of Presence that turned the affected Matoran into an involuntary audio and visual transmitter for their squad. enforced order through VahkiVahkiMetru Nui's mechanical law enforcement squads, designed to maintain rigid order but ultimately undermined by chaos beyond their programming. units assigned to the district. They policed the MatoranMatoranThe most abundant species in the Matoran Universe, chosen by Mata Nui to inhabit and maintain his cosmic body. and maintained the Brotherhood of MakutaMakuta (Species)Shadowy Antidermis beings and the Brotherhood's elite, Makuta commanded darkness and shaped the Matoran Universe's fate.'s grip on the underworld. When chaos came to Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive., when the Toa fell and the city fractured, Onu-MetruMetruIn the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it.'s miners and archivists had to adapt or perish in the darkness they knew so well.
Compiled from primary sources by Lore Fortress editorial. Reviewed by Joe Garratt, Editor-in-Chief.
Sources
- WikiBiosector01: Onu-Metru
- BookBIONICLE Adventures 3: The Darkness Below, Maintenance tunnel discovery
- VideoBIONICLE 2: Legends of Metru Nui, Great Disk locations
- SerialThe Mutran Chronicles, District alignments and conflicts
- BookBIONICLE Adventures 4: Legends of Metru Nui, Tunnel navigation sequences
Spotted a factual error or a primary source we missed? Email a correction. Every flagged claim gets reviewed.
Followed from this entry

Metru
In the Matoran language a metru was a single district of Metru Nui; the city was divided into six such districts, one for each element, and the term covered both the place and the elemental community that lived in it.

Ta-Metru
The fire district where Ta-Matoran perfected their craft and powered Metru Nui's industry for thousands of years.

Metru Nui
The city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive.

Po-Metru
Metru Nui's Stone District, home to carvers whose work defined the city and site of an ancient conflict that threatened to divide it.

Nuparu
An Onu-Matoran engineer from Metru Nui who built the Boxor and rose to become a Toa of Earth despite no warrior destiny.

Darkness
The Dark Hunter who shadows the Shadowed One himself, waiting for any sign of weakness so he can kill his leader and take his place.
Mentioned in56 entries
Aiyetoro
Aiyetoro was an Onu-Matoran of Metru Nui who became a miner in Onu-Koro on Mata Nui, digging for ore beneath the island and honouring the Virtues of Duty and Destiny.
Archives Mole
Small, harmless burrowing Rahi engineered by the Makuta, originally native to Po-Metru and forced into the shadowy recesses of the Onu-Metru Archives, where their cooperative behaviour built living ladders and bridges through the lower levels.
Cavern of Historical Records
The underground chamber on Voya Nui that held the written history of the island and its Matoran until the Piraka Vezok destroyed it out of spite.
Chief Archivist
The unnamed Onu-Matoran who ran the Archives of Metru Nui, held the keys to its deepest sub-levels and answered to Turaga Dume.
Dosne
Dosne is an Onu-Matoran from Onu-Metru who helped build Onu-Koro on Mata Nui, fled it twice, and went back to Metru Nui to help rebuild the city.
Fikou
Small spider Rahi of Metru Nui and Le-Wahi, whose webs gave a stretch of the maintenance tunnels under the Onu-Metru Archives the nickname Fikou Web.
Kanohi Rau
The Kanohi Rau allowed its wearer to comprehend foreign written and spoken languages, and was most associated with Turaga Nokama.
Kanohi Ruru
The Mask of Night Vision granted clear sight in darkness, with the Great version providing limited x-ray vision and a blinding light beam used by Whenua to navigate the Archives and locate the Great Disks.
Kanoka Disks
The protodermis disks of Metru Nui, used for sport, self-defence and machinery, carried by the Vahki, and melted down to forge Kanohi masks.
Kraahu
The specialist Vahki combiner formed from Zadakh, Keerakh, and Bordakh components, the Kraahu carried knowledge centres throughout its body, could split apart to fight six directions at once, and as a single unit could spray a cloud of stun gas.
Kraawa
The Kraawa was a long-necked Rahi whose only defence was absorbing kinetic force and converting it into size. The one seen on Metru Nui got loose after the Great Cataclysm.
Kranua
The specialist Vahki combiner formed from Nuurakh, Rorzakh, and Vorzakh sets, the Kranua could turn itself into sand to chase lawbreakers through cracks and reform on the other side.
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