Mecha Gorilla (メカゴリラ) is the first boss in Sonic Labyrinth, awaiting Sonic at the bottom of a long, Ring-filled slope in Act 4 of Labyrinth of the Sky.
After first dropping onto the boss' platform, Sonic is initially assaulted by a horde of miniature exploding robot gorillas - just don't stand right in front of them and Sonic will be fine. The real boss then teleports into the arena. After firing off his black, Pacman-esque forearms to wander around the board, the gorilla renders itself defenseless and wide open for spin attacks.
It occasionally re-attaches its arms and teleports around just to make things a little more difficult. The boss relinquishes a Chaos Emerald upon being destroyed.