The Maintenance Tunnels

The Maintenance Tunnels were the underground network running beneath the ArchivesThe Archives of Metru NuiThe Archives of Onu-Metru were the central repository of Matoran knowledge and Rahi specimens, maintained by the Archivist Corps beneath the city's surface. of Onu-MetruOnu-MetruThe deep archive-city that made mining and historical records preservation the beating heart of Metru Nui. in Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive.. They were so tangled that they earned the nickname the Fikou WebFikou WebThe maintenance tunnel system beneath Metru Nui's Archives, named for how its paths twist like spider silk., after the webs left by the spider RahiRahiThe Rahi were the biomechanical wildlife of the Matoran Universe, built largely by the Brotherhood of Makuta, ranging from background fauna to engineered war beasts. that lived there. Only authorised Matoran, usually Onu-Matoran and Ta-Matoran, were allowed in, and they travelled the tunnels by cart. (BIONICLE Adventures 3: The Darkness Below; BIONICLE: Metru Nui: City of Legends)

Layout and the Fikou WebFikou WebThe maintenance tunnel system beneath Metru Nui's Archives, named for how its paths twist like spider silk.#

The tunnels were usually narrow and twisted, criss-crossing one another. 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. explained the nickname himself: the Fikou Web was named for what the spiders left down below, and because the tunnels crossed and twisted around each other. Matoran avoided the area as much as they could, and rumours spread of maintenance workers going missing. (BIONICLE Adventures 3: The Darkness Below)

At some points, hatches led up to the surface or into the ArchivesThe Archives of Metru NuiThe Archives of Onu-Metru were the central repository of Matoran knowledge and Rahi specimens, maintained by the Archivist Corps beneath the city's surface.. Pipes in some tunnels carried molten ProtodermisProtodermisThe engineered substance building the Matoran Universe, protodermis exists in countless refined states from mundane metal to diamond-hard crystal to the destruction-or-transformation force of energized form. to heat the rest of the city. One corridor led to the Prison of the Dark HuntersPrison of the Dark HuntersA covert detention site near the border of Po-Metru and Onu-Metru, used by Nidhiki and Krekka during their stint as Metru Nui enforcers and the cell where Lhikan mentored three future Toa Metru., once guarded by VahkiVahkiMetru Nui's mechanical law enforcement squads, designed to maintain rigid order but ultimately undermined by chaos beyond their programming. 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., and another to a gateway to the Canyon of Unending Whispers. (BIONICLE Adventures 3: The Darkness Below; BIONICLE: Metru Nui: City of Legends)

Some parts of the network had huge doors, like those in the Archives sublevels, behind which were storage containers. Exhibits too dangerous to keep above, such as Rahkshi and, in one case, a Muaka, were kept at the edges of the network. (BIONICLE Adventures 3: The Darkness Below; BIONICLE Adventures 4: Legends of Metru Nui)

Resident fauna#

FikouFikouSmall 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. spiders gave the network its name. Kuma-NuiKuma-NuiGiant rat-like Rahi that haunted Metru Nui's Archives before fleeing to Mata Nui., huge rat-like RahiRahiThe Rahi were the biomechanical wildlife of the Matoran Universe, built largely by the Brotherhood of Makuta, ranging from background fauna to engineered war beasts., lived in the maintenance tunnels below the ArchivesThe Archives of Metru NuiThe Archives of Onu-Metru were the central repository of Matoran knowledge and Rahi specimens, maintained by the Archivist Corps beneath the city's surface., particularly beneath Ta-MetruTa-MetruThe fire district where Ta-Matoran perfected their craft and powered Metru Nui's industry for thousands of years. and Ko-MetruKo-MetruKo-Metru was Metru Nui's frozen intellectual quarter, home to the scholarly Ko-Matoran race.. After the Great Cataclysm a small number of them reached Mata Nui, where village defence forces patrolled to keep them away. (BIONICLE: Encyclopedia Updated)

Swarms of Fireflyers nested in the furnaces and maintenance tunnels of Ta-MetruTa-MetruThe fire district where Ta-Matoran perfected their craft and powered Metru Nui's industry for thousands of years.. (BIONICLE: Metru Nui: City of Legends)

The shapeshifting Rahi KrahkaKrahkaKrahka is a Rahi affiliated with various groups and known to have worn various Kanohi; only one of her kind remains. also made her lair at the back of the web, and the noise of the Toa Metru's fight with her woke the TahtorakTahtorakMassive, articulate Rahi that turned against their Skakdi riders and nearly wiped out an entire civilization., which broke through to the surface and destroyed some of the tunnels as it escaped. (BIONICLE Adventures 3: The Darkness Below)

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

The best-known trip into the tunnels began when the Onu-MatoranOnu-MatoranEarth-wielding Matoran of the deep who adapted to darkness and built the Matoran Universe's defensive cavalry. NuparuNuparuAn Onu-Matoran engineer from Metru Nui who built the Boxor and rose to become a Toa of Earth despite no warrior destiny. found a leak in the Maintenance Tunnels where the sea could pour in, which was odd because the miners usually reinforced the walls. He ran to the Toa MetruToa Metru and Toa HordikaSix Matoran elevated by Lhikan to save their city, mutated by Visorak venom, and restored in time to deliver the population to safety. for help, and 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., a former Archivist, led them down. (BIONICLE Adventures 3: The Darkness Below)

Whenua took the team in by a hidden shortcut, opening a hole in the road that led to the Archives. They were attacked almost at once: a freak fog and the buzz of Fireflyers surrounded them until MatauMatauA former Le-Metru test driver who became a Toa Metru, Matau wielded air, illusion, and shape-shifting before sacrificing his Toa power to wake the sleeping Matoran., using the little elemental power he had left, blew the fog away to reveal two Rahkshi. Deeper in, the Toa split up, were turned against one another by Krahka's disguises, and were picked off one by one before they beat her in her lair and repaired the leak. The story is told in The Darkness BelowThe Descent into the Fikou WebAn expedition by the Toa Metru into the maintenance tunnels beneath Onu-Metru to investigate a seawater leak, ending in their first encounter with the shape-shifting Rahi Krahka.. (BIONICLE Adventures 3: The Darkness Below)

The Vahki transport#

The Toa Metru also found a Vahki TransportThe Vahki TransportThe multi-legged cargo vehicle built by the Vahki of Metru Nui and used by the Toa Metru to escape the city across the Silver Sea after the Great Cataclysm. in the tunnels. Later, after the Toa and LhikanLhikanToa of Fire, leader of the Toa Mangai, and the last Toa of Metru Nui, who surrendered his Toa Power to create the Toa Metru and died defending Vakama. stumbled on a Lohrak nest underground, they escaped in a Vahki transport, and it was in one of these that they carried Matoran spheres away from the ColiseumThe ColiseumCentral tower of Metru Nui, serving as government seat, akilini arena and, during Teridax's masquerade, the place from which the city's Matoran were rounded up into spheres.. (BIONICLE Adventures 3: The Darkness Below; BIONICLE Adventures 4: Legends of Metru Nui)

After the Cataclysm#

A thousand years after the Great Cataclysm, any damage it had done to the tunnels was repaired with the Staff of ArtakhaArtakhaArtakha is the master craftsman of the Matoran Universe, ruler of a hidden island where the Toa Mata came into being and the Avohkii was forged.. After a fragment of Aqua Magna struck the Great Spirit Robot, the Fikou Web was badly damaged along with the rest of Metru Nui, and its inhabitants later left for Spherus MagnaSpherus MagnaA desert world of ancient conflict that became the merger point of the Matoran Universe and Bionicle's true endpoint.. (Toa Nuva Blog; BIONICLE: Journey's End)