Winder

Winders, also known as Moldola, are moving row of fireballs monsters appearing in several Zelda games. These creatures cannot be defeated.

Winders originally debuted in A Link to the Past. There they appear to be centipede-like monsters that move along the wall. They also appear in Four Swords and The Minish Cap acting the same way. In The Minish Cap, they can be found in the Temple of Droplets, the Palace of Winds, and Dark Hyrule Castle.

Known as Winder in Phantom Hourglass and Moldola in Spirit Tracks, these electrically charged monsters travel along walls, and so much as touching one can hurt Link. In those games, they look like several Sparks strung together.

These creatures are invincible, so it is best to ignore them.

Trivia
Their appearance in A Link to the Past, Four Swords, and The Minish Cap is similar to the Moldorm from The Legend of Zelda. The similarity between the names, Moldorm and Moldola, should also be noted.