Ocean Base Boss
From Sonic Retro
The third boss of Sonic Advance 3, Eggman utilizes a frog-like machine that attacks from above. The machine leaps up, its legs the only thing visible and moves back and forth across the screen, before stopping and dropping back to the ground. The only way to attack this boss is to be right between both legs as the machine drops and nail Eggman in his cockpit. Gemerl is stationed just above the cockpit.