Koiara is a matoran who is the well known ecologist in the matoran universe
lore
Koiara is a famous matoran ecologist lived on the northern continent. He mostly went into jungle near to his village to study the ecology of the habitat. His enthusiasm over ecology often lead to danger, and the danger caused him to lose his left arm, and replace it with the robotic one. He has a close friend named Amissaon, a ga-matoran who mysteriously appeared in the village during the time slip.
Around 10000 years ago, turaga Dume send a message to Koiara suggesting him to become a teacher in ga-metru school. He agreed, and after that, he lived in ga-metru doing both teaching his students, and studying metru nui’s ecology. He eventually went back to his village 2000 years before Toa Mangai started protecting the city of legend.
When the great cataclysm occur across the matoran universe, an earthquake struct Koiara’s village, killing most of the villagers except few including his close friend. Unfortunately, Koiara could not survive. He later revived in the red star, but there was no way to get back to his village.