Yuxes are organic creatures created by the X-Naut Phds. Their only attack is shooting a halo ring at Mario and his partners. Yuxes also spawn Mini-Yuxes, which encircle the Yux and create unbreakable shields around the main Yux. So, if even one Mini-Yux is around the Yux, the Yux is invincible and cannot be damaged. The X-Nauts brought them along when they captured the Great Tree, and they guard many of its passages prior to the X-Naut's routing at the hands of Mario. Some immature Yuxes can be found being created in a lab in the X-Naut Fortress.