Xenomorph
From AvP Online Encyclopedia
A hostile extraterrestrial lifeform, of unknown origin that was originally encountered by the crew of the Nostromo on Acheron. In the words of one of the crew members, Ash, it was "the perfect organism; unclouded by conscience, remorse or delusions of morality." Basically, it was the ultimate killing machine, which explains why the Weyland Yutani corporation regarded the obtaining of a specimen for the biological-weapons division to be such a high priority, above everything else, including the lives of others. Two centuries later it was discovered that the Alien race could provide potential benefits, including new alloys and new vaccines, which is why aliens were cloned aboard the Auriga. Though little is known about the Alien's anatomy, Ash labeled it an "encephlepod".
The first stage in the Alien life cycle is the queen. She positions herself in a hive, using drones or warriors to bring potential hosts to her, where they are cocooned. The queen is rendered more or less immobile by her giant egg sac. The eggs she lays contain facehuggers. These are small, parasitic creatures with eight extremely strong legs and a strangling tail, allowing them to coil around the head of the host. Having immobilized the host, the facehugger inserts an embryo down the trachea and into the chest cavity. It later falls off and dies. The host may soon regain consciousness as the embryo gestates inside him or her, and may experience excess hunger, sickness and fatigue. When the embryo is mature enough to survive without the host, it becomes a chestburster.
The alien tears its way out of the chest cavity through the ribs, also tearing apart the internal organs in the process, which kills the host. The new alien grows rapidly. More cases than not it will become just another drone or warior, and if near to a hive, will serve a queen. Lone aliens are seen to be far more hostile, perhaps because the survival of the one is now more important than the survival of the many, or the queen, the attitude adopted in the HIVE situation. Occasionally (and this depends on the embryo in the facehugger), then embryo will develop into a queen, the alien which lays the eggs. The gestation period of a queen is longer than the gestation period of a normal alien.
The adult alien is quite a beautiful and remarkable creature. Probably the most striking feature of the drone is the large, disproportionate head. Many of the creatures have been seen to have a translucent ‘cowl’ over their heads, under which can be seen a series of bony ridges. But other aliens have been seen with these same bony ridges, but without the cowl covering them. This may be a genetic change in some Aliens, like some humans have blue eyes and others brown eyes. Hidden inside the head is a second set of jaws, often referred to as a ‘maw’ or ‘tongue’. This is comprised of extremly powerful muscles and can be shot out of the mouth at incredible speed, and makes for an efficient weapon.
Aliens often take on the physical characteristics of the host. For example, if the host is a biped, such as a human, then the chances are that the alien will be, as well. That is not to say the they cannot run on four legs, though. The legs are particularly powerful for their size. The alien is extremely agile: it can run and leap and tear flesh apart with remarkable ease. Though it has five toes, it has six fingers, which is not inherited genetically from the host. Four of these fingers are joined; not together but in pairs, with an unjoined finger at either side. There are strong claws on both hands and feet.
Another striking feature is the exterior skeleton. The bones, muscles and tendons can all very easily be seen. The back of the alien is also quite remarkable. Extremely supple, but also strong it tapers into a long, segmented tail that also makes a terrific weapon. The creatures use this spined tail to impale and slash at their victimsy. Along the back are two pairs of dorsal tentacle-like appnedages, a pair on either side. There is also another a strange, exterior secondary spine jutting out from the back between the pairs of tubing. These aliens have concentrated molecular acid for blood.
Through genetic engineering, it is possible to create a queen that doesn’t lay eggs, but has an external womb.
These aliens are also referred to as 'Xenomorphs'. It was discovered in 2142 that the Xenomorphs were a form of "higher power", used to punish corrupt races in the known universe, and were the sole cause of the extinction of the entire Space Jockey race. "Xenomorph" is also a USCM term used to describe extraterrestrials, but after the infestation of Earth, it became a species name for the aliens.
