The Xeonomorph is the technical term for the race of aliens which are the focus of the Alien movies.
Types of Xenomorph
Facehugger: Released from alien eggs, these are short-lived creatures that have only one purpose: to find a host (usually human) and attach themselves to its face, where it injects an alien embryo down the throat of its victim. They are about a foot wide, with grasping finger like appendages surrounding its mouth/injector, and a tail. It's strong and fast, but shortlived. It has extremely acidic blood.
Chestburster: immature form of the main xenomorph type, the xenomorph bursts from the chest of its host, killing them. About three foot long, and snake-like at birth, the chestburster quickly grows into a mature xenomorph, shedding its skin.
Mature Xenomorphs: the main type of alien, they are about 6-7 foot tall (not including a long, prehensile tail), roughly humanoid, black, with an elongated head with double jaw (ie, a second set of jaws inside the first set capable of extending from the first set), insectile body, arms and legs with razor sharp claws, which allow them to climb walls and ceilings with ease. They are semi aquatic and capable of surviving a vacuum. Like all Xenomorphs they have highly acidic blood. They perform a function similar to worker/soldier ants in an ant colony. They are also capable of secreting a resin-like substance with which they build hives.
Queen: The queen is similar to the mature xenomorph, except it is larger, has a much more elongated head, and is often connected to an egg-sac. It performs a similar function to the queen in an ant colony, controlling the workers, and creating eggs.
Various other types of xenomorph ( the Newborn, aliens from different hosts etc. ) have also been invented, but these are the main, and coolest types of alien.
hatches from egg
and attaches to host
, implanting alien embryo
Embryo modifies host
to accomodate it and absorbs some of its DNA
Embryo matures into chestburster
, and emerges from host's chest
matures into fully grown xenomorph
Queens are produced when another queen lays a special queen egg, and have a similar lifecycle to a normal xenomorph.