Jumpers were tiny microscopic wormlike creatures native to Zelos II's Bare Forest. The parasite would infest and swarm the body of a deceased sentient, reanimating the corpse and giving the impression that the being had returned to life.
It was theorized that they emitted enzymes that electrically stimulated the brain to perform the process.
Creatures animated in such a fashion inspired superstitions about zombies among the native Zelosian people.