Mettaur, also known simply as Mets, are small modular worker robots. A Met consists of a black head in a yellow construction helmet, but can be attached to larger robotic bodies with arms and legs.
After defeating Bomb Man, Mega Man heads to confront Guts Man in a quarry. Mega Man sees a construction helmet lying on the ground nearby and bends to pick it up, believing it had belonged to a quarry worker. However, when the helmet reveals itself to have a head, Mega Man is forced to dodge its attacks and avoid the swarm of Mettaur around him. Suddenly Mega Man spots what seems to be a quarry worker unaware of the surrounding danger, and dashes over to warn him. But when the worker turns around, he is revealed to be a Mettaur with a body. Mega Man manages to escape and make his way to Guts Man. (MM #2)