An ancient Toa of the Green.
He is so old that his original armor and tissue had begun to disintegrate. He used his power over the green to craft armor and tissue from it. He has had to replace so much of his original form, he is more plant than Toa. This is something of an advantage, for he can easily heal himself if he is wounded in battle.
The grey represents the bones/armor of his original form; the metallic green represents where the plant life and his original armor are beginning to blur; the brown and the light green represent the plant life.
His weapon is made of black wood and thorns, so he can shift it from a glaive (hand-to-hand fighting) into a bow (long-range).
To emphasize his age and wisdom, I gave him a Turaga-esque appearance from the side.
His name comes from the Latin words for old and oak.
Inspired by Treebeard, from Lord of the Rings.