The Facehugger is the parasite that hibernates inside the egg. When a host comes in close proximity to the egg it triggers the parasite within to come to life and launch itself out of the egg at the potential host. The Facehugger puts the victim in a comatose state and controls the amount of oxygen he or she receives by forcing a tube down his or her throat. Wind "bags" on the sides of the Facehugger pump air through the tube, and the same tube is used to place an alien embryo within the host's chest cavity. After the embryo is planted, the Facehugger leaves the host's body and dies.