Iron blocks are recurring obstacles in Hey! Pikmin. They are meant to be pushed by Pikmin, in order to progress in an area or access a special place that is otherwise unreachable. They exist in two variants: the regular iron blocks, which need at least 4 Pikmin to be pushed, and the huge iron blocks, that need at least 8 Pikmin. Stony Flint Beetles can also push iron blocks, which can prove deadly to Olimar or the Pikmin. The player can also make Olimar walk into the iron block to make him push it, although this has absolutely no impact and is merely aesthetic.
Every time these blocks appear, pushing them has a purpose: