A famous image depicting Pac-Man chasing The Ghosts.

The power pellets are what Pac-Man invented in order to consume The Ghosts. He cut them out of Cheezus himself, giving him the cheese-esc look. They are little balls of pure holyness, and when consumed by Pac-Man, it causes him to shine in such a way that the ghosts are blinded, and easily attackable. This makes them run rampent, and their emergency blue gleam go off. They were meant specifically for The Board.