Iron ball

An iron ball is an obstacle taking the form of a plain metal ball. Iron balls are always placed at the top of a slope, rushing down a fixed path once the twenty Pikmin needed to push it have set one in motion. With its momentum and weight, it will break open walls the Pikmin themselves could not have torn down, opening entrances and exits to other parts of an area. Creatures in the ball's path will be killed, but so will Pikmin that aren't Rock Pikmin.

=In fanon games=

In Pikmin: Shipwrecked Stargazers
An iron ball can be found in sublevel three of Collapsed Reef in Pikmin: Shipwrecked Stargazers. It is held within a branch of coral and must be pushed to break through a cage of dead, bleached coral skeletons to reveal the Coarse Surfboard. Unlike those in, this one does not disappear upon reaching the end of its rolling course. Instead, it slams into the thick crystal wall and slightly but harmlessly cracks it.