Despite his scary appearance, he is quite friendly. Rrarrg's name originates from the one of the only noise he makes. Rrarrg has a light purple backside, lavender arms, and legs, along with a tan belly. Rrarrg also has barnacles growing on his back, chap dark purple lips and chipped teeth.
Patrick accidentally opened a toxic waste can which poured radioactive waste on a group of purple barnacles which caused them to fuse together to become a giant monster.