Zim is a short, green-skinned alien from the planet Irk. He has round teeth, a long worm-like tongue, and ruby-coloured eyes. His most distinguishing features are his pink antennae, which seem to have some sensory function. As a member of the Irken empire, Zim wears a standard red uniform with black accents. Beneath this uniform is his PAK, a mechanical device fused to his spine that provides life support and contains all of his memories and skills. Zim is over-the-top an theatrical.