The Ko'zal worm is a creature native to the Protoss homeworld of Aiur. Growing to sizes comparable to a small snake, it is not one of the most aggressive beasts on the planet. The Ko'zal worm is notable for its ability to produce a very strong type of Ko'zal silk when cocooning itself. Once the worm emerges as a moth and leaves the cocoon, Protoss workers would harvest the silk for clothing.