Ball

The Ball is a trap that appears in the Eastern Palace and Eastern Temple of A Link to the Past and Four Swords Adventures respectively. It is launched from huge openings in the dungeon walls and careens down corridors and across rooms. They will either appear in an endless and varied stream from a larger opening or are fired one after the other from smaller ones. Multiple launch points can lead to a lot of confusion as Link is forced to dodge and weave between the continuous assault of the giant metal traps. Larger openings can also occasionally launch Gargantuan Balls.

In Four Swords Adventures it is possible and sometimes necessary to avoid the balls by travelling to the Dark World.

Gargantuan Ball
The Gargantuan Ball is a particularly huge steel boulder that often appears at the end of a stream of smaller balls. If Link has not progressed far enough down a corridor to escape to reach a point of safety, this huge ball will be impossible to avoid and crash straight into him. In Four Swords Adventures, these balls will also sometimes fall down from above when certain switches are hit. They will then chase the four Links with apparent sentience, or possibly some kind of magnetism, and constantly hound them even down to lower floors. The only way to escape the giant metal menace is to pass through a small passageway to escape and return to a higher floor.

Trivia

 * Gargantuan Balls look very similar to Big Steelies in Super Mario World.