Krana

"Beware the Krana! When worn, they can steal the mind... and not even a Toa might be able to resist their power."

- Turaga Vakama, Comic 4: The Bohrok Awake

Each Bohrok contained the Krana which acted as its brain and gave it its power. The Krana, besides controlling the Bohrok, provided the intelligence to the swarms.

History
The Krana were created and telepathically guided by Cahdok and Gahdok, the twin Bahrag queens of the Bohrok swarms. If the queens were either not awake or had their connection servered, the Krana, and therefore the Bohrok extensively, would not be able to operate to their fullest performance.

The Krana, while the Bohrok's power, was also its weakness: even the strongest Bohrok, without its Krana, became little more than an empty shell, which could then be programmed or trained to repair the damage it inflicted. One of the main functions of the Bohrok Va scouts was to replace a Bohrok's missing Krana. If one felt threatened, it could eject from its Bohrok host; this left the host powerless, but if the Krana attached onto another being's face, it took control of that being's mind and assimilated it into the swarm.

The Toa Mata collected 48 Krana, 8 for each Bohrok breed, and placed them into special slots in the middle of the Bohrok nest. This unlocked the hiding places of six sets of Exo-Toa armor and the lair of the two dreadful Bahrag twins. When the Bahrag were defeated, the Bohrok shut down and the Matoran collected, pitted and sealed all their Krana away.

Recently, the Toa Nuva were sent on a mission to free the Bahrag, so they could release the Bohrok to return the island of Mata Nui to what it was "in the Before-Time" as Lewa said.

Types
The eight types, which follow, represent a rank in the swarm:


 * Xa: Swarm Commander. They lead their Bohrok on their mission. Bohrok Xa command a single swarm.
 * Za: Squad Leader. They have the ability to communicate telepathically with other Krana of the swarm and lead squads comprised of the remaining 6 ranks below. There are several Bohrok of this rank so that the swarm can be divided into smaller groups of 6 other ranks led by a Bohrok Za, thus providing the right Krana for any situation in all areas subjected to their search protocols. This Krana controlled Lewa and Turaga Matau for a period of time.
 * Vu: Surveyor. Bohrok of this rank can fly short distances ahead of the swarm to confirm that the path is clear.
 * Ca: Clearance. They have strong defense shielding; these Krana spearhead the swarm's mission.
 * Yo: Mole. They use their Bohrok to tunnel through anything on the island.
 * Ja: Scout. They have radar-like senses that detect distant obstacles in the path of the swarm and can help make a swarm aware of possible danger or a hold up.
 * Su: Worker. They have colossal energy and inhabit the strongest of Bohrok. They are always around whenever brute force is needed.
 * Bo: Sentinel. They can see in the dark and serve as night-time lookouts and lead their Bohrok into the darkest places on Mata Nui.

Colors
Each breed of Bohrok wore a different colored Krana. The Bohrok's Krana color corresponded with their colored eyes:


 * Blue: Tahnok
 * Orange: Gahlok
 * Red: Lehvak
 * Green: Pahrak
 * Yellow-Green: Nuhvok
 * Light Blue: Kohrak

Dormant
The colors of the Krana, while dormant and carried by a Bohrok Va, were different:
 * Yellow: Tahnok Va
 * Purple: Gahlok Va
 * Dark Grey: Lehvak Va
 * Tan: Pahrak Va
 * Black: Nuhvok Va
 * White: Kohrak Va

Availability
A Krana was packaged at random with every Bohrok set; the probability of the Krana being a Xa, for example, was 1 of 8 for each Bohrok breed.

Trivia

 * The "Fohrok", unlike Bohrok, were not controlled by Krana.
 * The Krana would work just as well as a Kanohi on a Matoran's face to keep them awake and alive; however, it also means that the Krana may be able to easily assimilate the Matoran if the Bahrag were awake.
 * In the Metru Nui Archives, Toa Metru Whenua once nearly knocked over an exhibit of Krana.