Rex is the biggest and meanest carnivore in your forest. Adding red nutrients to an Ellyps egg will produce a Rex. They will terrorize basically any animal smaller than itself so any nearby Dots, Ellyps, or Oozies are in trouble! They will also feed on animal carcasses just like the Ellyps. When they are not terrorizing your own creatures they are some of the strongest animals available to defend your forest from the evil robots.
Rex is a born fighter and is not known to run from a fight! Not even from overgrown zippo lighters!