Kraata Cave

On the outskirts of Po-Wahi was a massive hidden cave, where the Turaga of Mata Nui stored all the Kraata they captured during the Dark Time in which they and their master, Makuta plagued the island.

History
After the one year of peace that the Matoran and Turaga enjoyed on the island of Mata Nui, Makuta Teridax unleashed an all-out assault on the islanders with an army of Rahi beasts he had fitted with infected Kanohi masks; the Kraata, slug-like creatures formed from his essence, were responsible for the creation of these tainted masks; any Kanohi they touched became rusted and pitted, and its wearer a slave to Makuta's will. To protect their villages, the Turaga used all their wit and cunning to trap and capture the Kraata one by one, and sealed each one within a small Stasis Tube, rendering them harmless; they stored the fruit of their labors inside a large cave far away from the Matoran. Eventually, the collection of Kraata became so expansive that the cave's walls were lined with row after row of the comatose slugs. The Turaga kept this a secret from the Matoran and Toa, deciding only to reveal its existence when it was absolutely necessary for the Toa to know.

This time would eventually come shortly after the discovery of the Mask of Light, and the journey of Takua and Jaller to find its owner, the Seventh Toa. Determined to prevent the existence of a Toa of Light, Makuta created and unleashed his sons, the Rahkshi, upon the island. Having decided that the Toa Nuva would need to know more about the nature of their new enemies, Turaga Whenua led Toa Pohatu and Onua Nuva to the cave, and revealed to them the centuries-old collection of Kraata.