Bohrok

The Bohrok were a race of hive-minded mechanical insectoid creatures, controlled by strange, parasitic creatures within their heads, known as Krana.

Creation
It is unknown who the creators of the Bohrok were, whether they were originally created by the Great Beings, or built by an advanced race somehow related to the Krana. Regardless, they were stored for a later time, and for the purpose of restoring an island to its "before-time" state once the locals had left.

Metru Nui
In Metru Nui, Onu-Matoran miners stumbled upon a Bohrok nest and found that the creatures were fully mechanical while the Krana they carried inside were completely organic. After a quick check, archivists found there was no evidence of assembly. Another Onu-Matoran archivist named Mavrah theorized that the Bohrok were once biomechanical (like every other Bionicle lifeform), but evolved to a state with no organic parts and without a single independent thought. Although the Archives were eventually destroyed, the Bohrok nest for reasons unknown was untouched. However, word of their sleeping threat somehow spread to the public, including the Toa Metru.



Early Signs
Bohrok were since subtly warned against by the Toa Metru-turned-Turaga, and on Mata Nui, signs began to appear in various places. Inscribed on a rock in Le-Wahi were the ominous words, "Wake one, and you wake them all "(seen left). During his frozen exodus in Ko-Wahi, Takua received a vision of the Bohrok symbol.

Awakening
Takua would later play a major role in the awakening of the Bohrok. At the climax of the battle against Makuta in Mangaia, he would record--and create--history. When the Toa Mata defeated Makuta, the evil spirit subtly went to the part of chambers that connected to the Mata Nui Bohrok Nest. He opened the gate, and lightly touched some Bohrok still in their pods. The curiosity of Takua got the better of him, and he wandered inside. The words, "Wake one, and you wake them all" came to fruition. Takua barely escaped using an ancient chute, but the Bohrok were  still awakened.

The Bohrok War
The Bahrag were confronted with a new problem: the Matoran were still living on Mata Nui. Yet, the order to cleanse the island was still given, and the order had to be followed. They decided, partially influenced by the Krana, to attack anything directly in violation of their mission. The Bohrok quickly developed a system for war (which might have been one of their purposes all along) and came above the surface.

Surprise Strike
Expecting a great victory celebration for the defeat of Makuta, the Toa returned to their respective Koro only to find with horror that new insect-like Rahi were starting to destroy them. In Ta-Koro, the deterioration was especially great, and it was the site of the first battle and victory for the Matoran. The Bohrok easily felled large trees, froze lava, melted ice, and leveled mountains in their devastating quest to "clean it all".

Skirmishes and Counter-Attacks
The Toa fought in several difficult battles involving all of the elements, but it was at the home front where the real battle was fought. Lewa shockingly found that the whole of Le-Koro had been taken over by Krana and put into the hive. Taking the Matoran hostage, Bohrok-Matau forced Lewa to wear one himself, and subject to their will. Only Tamaru and Kongu escaped. Meanwhile, Kopaka discovered the second entrance to the Bohrok nest at Mount Ihu.

Boxor


At Onu-Koro, the village and mines were being flooded by a squad of Gahlok. Needing to improvise, the inventor, Nuparu found for the first time in a thousand years that the Bohrok were mechanical. This vital fact allowed the Onu-Matoran to reverse-engineer defeated Gahlok into fearsome new fighting machines that would turn the tide: Boxor. Boxor were specifically designed to battle Krana-controlled beings by using quick jabs and punches to knock them off. They were extremely effective, and liberated the Koro from several attacks, including--with the help of an ambush planned by Takua, Kongu, and Tamaru--Le-Koro's Krana infestation. However, they weren't foolproof.

Endgame
Ga-Koro was attacked by a swarm of Pahrak in an infamous battle where the Boxor were for the first time defeated, and a new kind of Kolhii was invented.

The Toa were finally free to take the battle to the Bohrok, and they went inside a strangely-empty nest. They found buried Exo-Toa, placed there in the case that the Bohrok rose up. They used them to fight the Bahrag, but soon found that it limited their elemental powers that allowed them to defeat Makuta and his minions in the first place. They defeated the Bahrag, but not before mutating in chutes of energized protodermis, becoming the Toa Nuva.

Reprogramming
The Bohrok lost their Krana, and were reprogrammed to serve the Matoran. However, this lasted only briefly, as they were destroyed or put back to sleep by the Bohrok Kal.

Bohrok Kal


Shortly afterward, six mutated Bohrok called Bohrok-Kal were released. These elite Bohrok were much more powerful, intelligent, and independent than regular Bohrok. They also used unorthodox Elements. Their mission was to release the Bahrag from where they had been imprisoned by the Toa Mata, thus enabling the Bohrok swarms to resume their invasion. Initially, they won their battles against the Toa Nuva and reprogrammed Bohrok, stealing their Nuva Symbols. They were confronted at the Bohrok nest attempting to free the Bahrag by the Toa Nuva. Toa Tahu unveiled the Vahi, Kanohi Mask of Time. It didn't defeat the Kal on its own, but it gave the Toa time to reverse the Kal's powers back upon them, destroying them spectacularly.

Mahri Nui
It has been hinted at that the Bohrok have some connection with Mahri Nui.

Swarms and Systems
The Bohrok are divided into six swarms: Tahnok, Gahlok, Lehvak, Pahrak, Nuhvok, and Kohrak. Each has a unique style of war, thought, and "cleansing".

Bohrok Va
The Bohrok Va are secondary Bohrok, or "drones". They do the duties of Krana-exchange, courier, strategist, and general petty work. While not nearly as powerful as their stronger brethren, they could be considered smarter, and can still put up a fight.

Powers
Bohrok have the ability to curl up into a ball and eject their Krana onto an opponent, making them a "host". Each Bohrok is also equipped with "hand" shields that allow them to fire their specific "cleaning" agent, be it acid, flame, or otherwise.

Krana


Krana were intrinsic to the Bohrok swarms; without them they were blank slates. The Krana formed a telepathic bond with the Bohrok and each other, effectively forming a network ultimately controlled by the Bahrag. The Krana also gave them additional powers.

Behind the sets

 * It has been hinted at that the Toa Mata and the Bohrok are somehow related, based on a comment by the Bahrag.


 * Some Bohrok appeared in the Maze of Shadows video game, which took place well before the swarms were awakened. It interestingly turns out that these Bohrok were not controlled by Krana, but rather by Kraata that had escaped a Brotherhood of Makuta lair. They found their way into a Bohrok nest, took over some Bohrok shells and learned how to use them to defend themselves.


 * The two theories concerning the Bohrok's creation are very similar to the debate between the theory of Evolution and Creationism or Intelligent Design.


 * The Krana are similar to the Goa'uld of Stargate SG-1, being a parasitic egotistical race that takes on "hosts".

Appearances

 * Mata Nui Online
 * Bionicle.com supplements
 * BIONICLE Chronicles 2: Beware the Bohrok
 * BIONICLE Chronicles 3: Makuta's Revenge