Sign Ball

 is a ball that appears in Wreck Ball Survival.

When it's green, it moves across the map freely; when it's red, it doesn't move at all unless a player moves. If a player moves while Sign Ball is red, it charges at the player at an extremely high speed.

One touch of the ball leads to instant death regardless of its color.

Trivia

 * While hunting down a player, Sign Ball might kill another player if they're in its path.
 * In Ball Gallery, Sign Ball is shown as two separate balls, while it is, in effect, one ball with two different forms.