Iron ball

The Iron Balls are objects found throughout Pikmin 3 that serve as an interactable obstacle, much like the paper bags. They are very plain metallic-grey orbs with a number written on them, usually a 20, such as with the one found at the Yellow Onion in the Distant Tundra, which is also the amount of Pikmin required to move it.

Iron balls are always placed at the tip of a slope, so they will rush down a fixed path once the Pikmin have set one in motion. With its momentum and weight, it will break open walls the Pikmin could not have torn down themselves. This opens entrances and exits to other parts of an area. Creatures in the balls path will be killed, allowing the player to defeat enemies in some rare cases, but Pikmin are more likely to be crushed if the player does not pay attention. Rock Pikmin will survive the hit.