Kanohi

Kanohi Masks are masks worn by Matoran, Toa, Matoran, Great Spirits, and sometimes Rahi. They are needed for the creature to survive. There are many Kanohi, but are split into the following groups:
 * Great Masks - used by Toa and Great Spirits. They give the user great power.
 * Noble Masks' - used by Turaga. Noble Masks are less powerful than Great Masks but still have some abilities.
 * Matoran Masks - used by Matoran. They have no powers.
 * Infected Masks - used by Makuta to put Rahi under his control. Infected Masks, if worn by a Toa, will turn them evil.