The Bead Worm Boss (デンジャラス・ボールタワー Denjarasu Bōrutawā?, lit. "Dangerous Balltower") is the Master Robot of Gigalopolis Zone in Sonic Chaos. It is a larger, looser variation of Caterkiller built by Dr. Robotnik, and is the second boss of the game.
After passing through the tunnel pipes in Gigalopolis Zone Act 3, Sonic or Tails arrives in an empty space, where the Bead Worm Boss emerges from the ground. After this, it will individually release all three of its spiked segments in a pattern, which the player must avoid. The patterns are as follows:
- The first segment is thrown diagonally into the air.
- The second segment is thrown horizontally in front of the Bead Worm Boss.
- The third segment is thrown diagonally into the air.
After this, only the head of the Bead Worm Boss is left, but only for a few seconds, as the robot creates another three segments and emerges from the ground once more, repeating the same pattern. The Bead Worm Boss will wobble when damaged. After eight hits on Master System or three hits on Game Gear, the Bead Worm Boss is destroyed and the player moves to the next Zone.
- The Bead Worm Boss was originally unnamed in the Master System manual; however, in a Sonic The Comic Q Zone that covered the game, it was alternatively dubbed The Robo-Snake!.
- A slightly similar robot called Wood Buttarundorf is the third boss in Sonic the Hedgehog Triple Trouble.
- In the Nintendo 3DS version of Sonic Lost World, larger versions of Sandworms are encountered and heavily resemble the Bead Worm Boss due their size and color scheme.
- Knuckles encounters a very similar battle with the Uber Caterkiller at the end of Act 1 of Mirage Saloon Zone in Sonic Mania. The only noteworthy difference is that it is colored purple and yellow.