Bob-omb Ball

From the Super Mario Wiki
Bob-omb Ball.

A Bob-omb Ball is one of the balls that can be used in Mario Party 5's Bonus Mode game Beach Volleyball. Every hit, including a serve, makes the digit count down from ten. When zero is shown, the Bob-omb Ball explodes before the team can hit it and the opposing team gains a point. A point can also be scored if the Bob-omb Ball, like a regular volleyball, hits the sand.