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. It attaches itself by wrapping its tail around the victim's neck, causing him or her to gasp for air. For protection, Facehuggers have concentrated acid for blood and will strangle the host with its tail if there is any attempt to remove it. They have an outer layer of protein poly-saccarides and can shed their cells and replace them with polarized silicon, which gives the facehugger a stronger resistance to harsh environmental conditions.