Mega Ball

Mega Ball is a weapon unique to the Mega Man 8 game, and Mega Man gets it in the intro stage. He can kick this at enemies, as some enemies (like Atetemino) can only be hit with this. Holding up on the control pad will make the ball go at a higher angle. However, it takes practice to kick it and hit well. It can also be used to reveal hidden items such as a 1-up in the beginning of Clown Man's stage

This ball can also be bounced off of (even in midair) to reach hard-to-reach areas.

The Mega Ball is one of Mega Man's special weapons in the Marvel vs. Capcom games. In it, it's called the Rockball.