Hedron

The Hedron is an obstacle in Super Paper Mario. It is encountered in the Outer Limits. The Hedron is an indestructible, rotating, blue rectangle with a yellow outline. If Mario is hit by it, he takes damage. Hedrons are often encountered in groups and must be avoided with quick, evasive, maneuvers. Flipping to 3D does not help, either, as the Hedron exists in the third dimension as well.

Trivia

 * The Hedron's name comes from a geometry suffix.
 * Hedrons move in a way similar to Helirins (which were originally from the game Kuru Kuru Kururin) from Super Smash Bros. Brawl.