Eerie

Eeries are ghosts that appeared in Super Mario World. They fly in straight or wobbly lines, and usually come in packs. Mario or Luigi get killed when they touch them. They are in most of the Ghost Houses in Dinosaur Land and can only be defeated with invincibility.

Trivia

 * Eeries have a minor resemblance to Baby Yoshis and Spikes. This may suggest a relationship to either.