"Subterranean"

"Subterranean" was a former Onu-Matoran and Dark Hunter.

Toa\Dark Hunter War
During the Toa/Dark Hunter war in Metru Nui, an Onu-Matoran was trapped in an Archive tunnel when it collapsed. Over time, he somehow mutated into his current form. It is likely that he was mutated by a substance in an archives display case, possibly a mutagen.

Dark Hunter
After escaping from the tunnel, his new form scared his friends, and in grief he left the city with the Dark Hunters, as they were expelled from the city after the war. He is currently trying to arrange an alliance between the Hunters and a tribe of Frostelus on the grounds that he is one of the few creatures uglier than they are.

Powers and Abilities
"Subterranean" could disassemble objects by touching them, and could immobilize enemies just by looking at them. His major weakness was sound, as even the slightest whisper was painful to him; he wore special armor that dampened sound to compensate. Still, The Shadowed One stated that he tries to avoid a Toa of Sonics (possibly Krakua), who has the potential to kill him, as much as possible.