The Golemech is a large ape-like robot with its weak interior protected by an outer shell of stone. He is found on the Easy version of Venom in Star Fox 64.
Fighting him
The Golemech immediately begins to flee when the player approaches it because Andross had not yet completed it. However, what appears to be cowardice is soon revealed to be a cunning strategy as the boss leads you down a long stone hallway with little room to maneuver. In the hallway, the boss periodically slams the wall, ceiling, or floor to cause pillars of stone to come shooting out at the player in all directions.
Luckily, this is its only tactic and the only other danger is the monkey enemies that periodically appear along the walls.
Shooting the boss causes its stone armor to fall away to nothing and revealing its soft core underneath.
Trivia
A similar enemy type and boss appear in Star Fox Command for the Nintendo DS.