The impaler colony is an antiquated zerg structure created by the Overmind millennia before the Great War. Its successor was the now-defunct sunken colony. Attacking with subterranean tentacles, its attack is slow, but does incredible damage. At least three impaler colonies survived on Marek V.
During the Second Great War, Ryloth's Brood came under assault by the Dominion's Prometheus Company. Kerrigan sent hydralisks to obtain its essence, which was used to allow the hydralisks to morph into impalers and destroy the terran forces.