Yadokargo

Yadokargo (ヤドカルゴ) is the boss of the opening stage in Mega Man 8, a crab-like robot that protects Dr. Wily's secret base, and accumulated moss on its shell due to the long time it stood still. He pinches at Mega Man, leaps, and shoots bombs. His weak point is his brain, which is protected by his shell. When hit by a charge shot or one Mega Ball, his brain is exposed. When visiting the stage again, he can be easily be taken out with Flash Bomb or Tornado Hold, and can be destroyed instantly with Astro Crush (regardless of protection from his shell). Also, if you have the Tornado Hold and fire it off right underneath him, he will take severe damage.

Trivia

 * His name is derived from "yadokari", Japanese for hermit crab.