The Egg Snake (エッグ スネーク) is the sixth boss in Sonic Advance, which takes place in Cosmic Angel Zone.
The player and the Egg Snake are on a mechanical chain made of balls. The player must jump close to the machine in order to shake the chain make Dr. Eggman face up, making him vulnerable to attack. The player must watch out not only for the spikes on the Egg Snake, but also for the slow-moving energy shots coming from the machine's hole. Eggman will fire three shots per round. Further adding to the difficulty of the boss fight is that there is nowhere for lost Rings to bounce on when the player takes damage, meaning it's very easy for the Rings to become unobtainable.
For the last two hits, Eggman will start moving much faster for a moment, which demands a fast reaction from the player. It gets faster the more the player hits him. The player must inflict a total of eight hits on this robot (or six in Easy mode) to defeat it. The player does not break open a Capsule after defeating this boss, and instead chases Eggman straight to the final Zone.