Creep

Creep was a living zerg superorganism, a viscous purple substance, thick and slimy to the touch, that the Swarm used to nourish its structures, larvae, and other strains. It was psionically sensitive and could be influenced and controlled by psionic entities. More than a mere secretion, creep bound every colony located on it into a single living creature, and if left unchecked it could consume an entire planet within days. (StarCraft: Uprising; StarCraft: Shadow of the Xel'Naga; StarCraft: Frontline Volume 2)

Seeding and spread#

Creep could be deposited in a number of ways. Certain zerg structures, such as hatcheries, served as loci for its growth, and hive spores could be used in the initial stages of infestation. Post-Great War evolution gave zerg creatures the ability to spread creep themselves, overlords secreting it directly and other strains laying creep tumors. Once established, creep spread rapidly, and its proliferation could be observed in real time. If left unchecked it could consume an entire planet within days. (StarCraft manual; StarCraft: Uprising; StarCraft II: Wings of Liberty)

Biology#

Creep had a cellular structure and could be considered an organism in its own right, with zerg structures functioning as its organs. It sustained itself and the surrounding Swarm by processing minerals drawn from the ground through deep tendrils, and it could envelop and consume biological matter, including the corpses of the fallen. Ground strains moved faster over creep than over normal terrain. Creep could grow in anaerobic environments and over water, and it could even extend over hollows in the terrain, though attempting to cross such a hollow could cause it to tear and give way. (StarCraft: Uprising; StarCraft: Shadow of the Xel'Naga; StarCraft: Liberty's Crusade; StarCraft: Speed of Darkness; StarCraft: Frontline Volume 2; The Education of PFC Shane; StarCraft Field Manual; StarCraft II: Wings of Liberty)

Function and removal#

A zerg colony became a single living creature through the interconnectivity of creep. Most zerg structures were effectively giant organs that drew sustenance from it, a notable exception being the extractor, and the zerg that lived upon it took their nourishment from it as well. Deprived of creep, they resorted to consuming other organisms, even one another, to survive. The substance also carried a network of neural connections that alerted the nearby hive to incoming intruders. (StarCraft manual; StarCraft: Shadow of the Xel'Naga; StarCraft: Frontline Volume 2)

Creep could not stand extreme heat and would not grow in unsuitably hot places. It could be set alight by high explosive or incendiary ordnance, but it grew back fast enough that brute force rarely cleared it entirely, and reliable removal could only be guaranteed by destroying the structures that served as its growth loci. It was often hard to tell when creep was truly dead, and protoss glassing was used numerous times to eradicate planetary infestation entirely. (StarCraft: Uprising; StarCraft manual; StarCraft: Speed of Darkness; StarCraft Field Manual)

Terran and protoss experiments#

The Terran Confederacy conducted experiments with creep after discovering xenomorphs on a number of fringe worlds. In secret facilities such as the Fujita Facility on Vyctor 5 and an installation on Tarsonis, researchers found they could grow creep from spores and control its growth with heat, and using ghost subjects such as Sarah Kerrigan they found it could be controlled psionically. The Vyctor 5 and Tarsonis experiments were later destroyed by the Sons of Korhal. (StarCraft: Uprising)

In 2502, the protoss scientific organization PAX, the Protoss Advance/Experimental Facility, conducted its own experiments, infecting creep with a virus in the hope of destroying all creep and committing xenocide against the zerg. The mutated creep proved infectious, engulfing two zealots assigned to the facility and infesting one of them, named Ruom. It became a psionic predator able to impede the Khala and drive nearby Khalai to madness, and Ruom went on a rampage that killed the other protoss. The entire facility was frozen and abandoned, only to be discovered later by a terran military expedition, which found the mutated creep still alive. (StarCraft: Frontline Volume 2; StarCraft II: Heaven's Devils)