The Rock Species are extremely bulky, and are quite stupid-looking. It can be assumed that they are indeed as slow-witted as their appearance suggests, as they were incapable of seeing through Invader Flobee's terrible disguise consisting of rocks strapped onto his body. Nevertheless, the Rock Species hailed Flobee as their king, and when Zim spied on the Invader through his telescope, Flobee was being fanned with large leaves by the rock creatures. The Rock Species made their first and only appearance in the episode "Planet Jackers".