 In the novel they are observed directly feeding on humans by draining their victims' blood using pipettes; there is also a speculation about them eventually using human slaves to hunt down all remaining human survivors after the Martians conquer Earth.In the film the Martians do not bring the novel's fast-growing red weed with them, but they are defeated by Earth microorganisms, as observed in the novel.However, they die from the effects of the microorganisms within three days of the landing of the first meteor-ship; in the novel the Martians die within about three weeks of their invasion of England.