This is simply a group of explosive tags wrapped into a ball and used in the same manner as a cannonball with the added explosive effect. They are fired from cannons and are capable of dealing heavy damage. There is also the special variant used as underwater mines.
The Explosive Tag Ball appears in the Ultimate Ninja Storm series as one the default ninja tools for several characters. In the games, the ball is thrown, bouncing then rolling on the ground before stopping. The ball will automatically explode if it comes in contact with an opponent or after a certain amount of time has pasted.