There are eight distinct life processes witnessed in the life cycle of the Xenomorph Alien. Much of the information to date is conjectural as there is little but Convict Morse’s books to base any research on. Information has been separated into verified information and conjectural theories.
Level 1 - Eggs
Duration of cycle: Undetermined
Activity: Responds to proximity by opening.
Locomotion: None
Attacks: None.
Deffences: Leathery outer shell.
Observed Facts: Eggs are created inside the Alien Queen and exit through a tube from her extended abdomen to stand upright on their own. The Egg is approximately 2.5 feet tall with a leathery, translucent surface, with four petals on top which open when a potential host enters its proximity. The Egg maintains the Facehugger within it over indefinite periods of time and with seemingly little nutrients in various environments. It is able to detect the proximity of a potential host through sound and/or movement. The dormant Egg then comes to life, with its top opening like the petals of a flower and releasing the Facehugger. The Eggs are extremely flammable.
Conjectural Theories: Possibly an organism unto itself. The root-like tendrils might explain how the Egg can nourish and maintain the Facehugger inside. The law of averages states that, on any given planet they are laid, the most prominent and therefore most successful creature will be the one encountering the Egg. Best anti-egg weapon to date has been the Flamer.
Level 2 - Facehugger
Duration of cycle: Undetermined
Activity: Responds to proximity by attacking.
Locomotion: Highly developed reflexes and instinct. Eight limbs and one prehensile tail for running and leaping.
Attacks: Grasping of face with greater than human speed and strength.
Deffences: Acid blood, silicon coated skin, speed and agility.
Observed Facts: 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. It then firmly grasps the victim's head with its eight spider-like digits. 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
Conjectural Theories: These things posses no more intelligence than sperm and work purely on reflex. They can not do complicated manoeuvring such as find a way through a maze. It is believed they have some sort of highly advanced sensory organs that help target. Area of effect or Automatic weapons work best against these since precise targeting is difficult
Level 3 - Impregnation
Duration of cycle: 1-4 hours
Activity: Actively resists movement.
Locomotion: None. Limbs used to constrict and grip the victim.
Attacks: Strangle and choke host.
Deffences: Acid blood, silicon coated skin, damage to host if removed.
Observed Facts: 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. 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. After the embryo is planted, the Facehugger leaves the host's body and dies.
Conjectural Theories: It is possible a memory suppressant is used in this process to avoid unnecessary agitation in the host and to limit the chance of action being taken to remove or quarantine the host. No device has been found to remove a facehugger without killing the host.
Level 4 - Incubation
Duration of cycle: 1-4 days.
Activity: Dormant.
Locomotion: None.
Attacks: None.
Deffences: Acid blood, silicon coated skin, removal may kill host.
Observed Facts: The host soon regains consciousness with no recollection of the implantation process.
The embryo continues to grow undetected within the host. The only sign of its presence is the occasion sharp chest pain. It will not restrict the activity of the host in any way, nor will the host retain any memory of the impregnation except vague recollections of dreams about smothering. The embryo develops quickly and eventually forces itself out of the host's chest, causing an extremely painful and violent death.
Conjectural Theories: It is believed that during this process the embryo uses some of the hosts DNA to "steal" some of the evolutionary advantages it has already. This process cashes in on the natural selection process already at work in the location. Complicated and Delicate surgery during while host is in cryo-sleep may prove effective. As yet the process is untried.
Level 5 - Chestburster
Duration of cycle: 4-24 hours.
Activity: Highly active.
Locomotion: Extreme speed run.
Attacks: Sharp jaws.
Deffences: Speed, acid blood.
Observed Facts: The life of the mature Alien begins once the implanted embryo completes its symbiotic gestation period within the host. It escapes through the host by bursting through his chest, causing an extremely painful and violent death. At this stage, the snake-like Chestburster has a small cranium and tan colored skin and ranges from one to two feet tall. After birth, the Chestburster will either feed on the remains of the host or seek shelter if threatened. It sheds its skin as it matures, its exoskeleton hardens and becomes darker, and its cranium elongates. Like the Egg, it is also extremely flammable.
Conjectural Theories: This is the most fragile time for the embryo since it’s host is no longer an effective hostage, and it takes some time to leave the carcase completely. Nor has it managed to cover itself in it’s silicon layer yet. The death of one of these upsets an entire colony, who respond aggressively. Flame works well against these creatures, but almost any weapon will.
Level 6 - Adult Soldier/Drone
Duration of cycle: Undetermined.
Activity: Highly active.
Locomotion: Fast bipedal gait, approximately equivalent to a human sprint. Capable of moving on vertical or inverted surfaces at speed.
Attacks: Intelligence, claws, teeth, second jaw, prehensile spiked tail, acid spit, strength.
Deffences: Silicon coated skin, acid blood.
Observed Facts: The Chestburster sheds its skin like a snake as it matures. Each shedding of skin and increase of body mass may cause the Alien to secrete or lose of some its acidic blood. Its entire maturation process takes only a few hours, and the eventual form of the beast may differ only slightly. The exoskeleton becomes harder and darker, and its cranium elongates as it gains it’s silicon cover. It rapidly grows in size (to over two meters tall), intelligence, and strength to become an adult Alien. Mature Aliens have concentrated acid for blood which they know they can use to their advantage. They have two mouths, one inside the other, the inner mouth being the Alien's tongue. The tongue can extend up to one foot from the Alien's mouth and its strong driving force can easily puncture a human skull. The adult Alien develops sharp claws and a spiked tail, which is used for both balance and attack. Spines on the Alien's back provide protection from attacks from the rear. Adult Aliens are also good swimmers and are equally deadly in and out of the water.
Conjectural Theories: Originally believed to be psychically aware of others, now it is believed they have highly advanced senses that are so unbelievably accurate that they appear psychic. Their form may be based on the DNA the embryo took, hence the "Dog Alien" on Fiorina "Fury" 131. It is also believed now that there are two distinct classes of Adult Alien; the Drone who acts to ensure that the Queen and her unborn are protected, and the Soldiers (like those with the ridged head on LV 426) who are quick and agile with great strength, making them difficult to kill. Soldier Aliens will find and immobilise suitable hosts while Drone Aliens will build and maintain the nest. Like insects, Soldier Aliens serve and protect their Queen, which is even larger and more dangerous. Automatic weapons with unlimited ammo and a huge range work best with these creatures.
Level 7 - Nesting Drone
Duration of cycle: Undetermined
Activity: Dormant (responds only to direct threats to colony)
Locomotion: None
Attacks: None
Deffences: Camouflage, silicon coated skin, acid blood.
Observed Facts: For some reason Adult Aliens have a tendency to become dormant and ignore humans.
Conjectural Theories: It is believed that after clearing an area of threats the Drones begin to use their mucus excretion to produce an organic style nest. They then are not needed until some new threat exposes itself and so enter a form of torpor. They can reawaken in moments though and are almost indistinguishable from their surroundings in the meantime. No weapons have been used against dormant Aliens except in one case the coolant from a shuttle. We do not believe this to be helpful in combating them. Best tip is, if they are dormant, GET OUT!
Level 8 - Nesting Queen
Duration of cycle: Undetermined
Activity: Active
Locomotion: None. Detachment from the ovipositor is painful and difficult. Once free may move as an Adult.
Attacks: Superior intelligence, elongated claws, razor teeth, lightning second jaw, massive prehensile tail with 2 foot spike blade on the end, acid spit, Powerloader equivalent strength.
Deffences: Silicon coated skin, acid blood, Hive Drones.
Observed Facts: The Queen is born in a similar way to the Soldier Alien, but her incubation period is longer - several days instead of several hours. Her cranium is much larger and flatter and she is approximately two to three feet taller than the Soldier. She also has four arms instead of two.
The Queen, similar to a queen ant, is the only reproductive female in the hive and directs its operation - from its construction to the location of suitable hosts. She creates and lays Eggs through the use of her extended abdomen.
Conjectural Theories: It is believed that she communicates her will through the secretion of pheromones or possibly by an empathic link. She is also believed to be more intelligent than the Soldiers and Drones, capable of understanding an manipulating technology. Best weapon to use against one of these is a Nuke. They are capable of surviving a hard vacuum and out wrestling a Powerloader.