Template:Buildingbox Creep Colonies help extend the Creep that is initially generated by a Hatchery. Creep is similar to blood vessels in the sense that it is needed for Zerg buildings to grow. When a Hatchery or Creep Colony (and variations) is built, it slowly generates Creep around it, eventually stopping when a certain radius is reached. If the source of creep around a building is destroyed, the building will still retain a minuscule amount of creep under it and will continue to live. Larvae are completely dependent on the Creep for nourishment and will die shortly if removed from it.
Creep Colonies also have the ability to evolve into a Sunken Colony (for repelling ground invasion) or into a Spore Colony (for detection and repelling aerial assaults). Thus the Creep Colony is not only necessary to expand the life-giving Creep but also for mutating into defense.