Each of the six villages on Mata Nui is ruled by an elder called a Turaga. As the oldest and wisest member of the village, the Turaga’s job is to be sure the ancient legends are not forgotten. The Turaga work together to protect the knowledge of Mata Nui’s past, as well as the prophecies about its future.

The Secrets of the Turaga

Since the Toa arrived on Mata Nui, the Turaga have been there to provide them with important information. The Toa learned about the Kanohi masks and the Bohrok swarms from the Turaga, and they have come to rely on the wisdom of the village elders.

But often it seems that the Turaga know more than they are telling. There are caverns that they have forbidden any Matoran to enter, but they will not say why. Some Toa Nuva have questioned why they were not told about the Bohrok before the swarms appeared on the island. It may be that the Turaga keep many more secrets than anyone knows…

Source: The Official Guide to BIONICLE