Death Ball (デスボール?) is a mini-boss from Sonic & Knuckles, as well as its locked-on form, Sonic the Hedgehog 3 & Knuckles. It is encountered in the second act of Death Egg Zone, before the fight with the Kyodai Eggman Robo.
The Death Ball floats from side to side between the two elevators Sonic or Tails can use to reverse gravity. The yellow bumper shield visible in the picture always positions itself between the Death Ball and the player, making it impossible to be damaged directly.
The only means the Death Ball has of attacking is by way of strange buggy-like objects that it drops from its mouth on its underside. These have wheels on the bottom and spikes on the top. If gravity is normal (so objects fall downwards) they will move around on their wheels, but if gravity is reversed, they will become lodged on the ceiling and not move at all. They explode after a delay of about twenty seconds. The player must cause the spiked buggies to accumulate on the floor, then enter one of the elevators to reverse gravity and have the character walk about on the ceiling. A Spin Dash is then required to throw the buggies off of the ceiling. If one hits the Death Ball, a hit is scored. A hit is also scored if a buggy "falls" from the floor towards the ceiling and hits the Death Ball on the way up. Eight hits are required for its destruction.