Xenomorphs are usually muted black, blue, or bronze with an elongated head, and varying numbers of fingers. They are carnivorous, and extremely hostile. Similar to many insects, they live under a caste society. Not much other than this is known, as there have been few encounters with them, and most have led to death of most, if not all, of those involved. Survivor accounts of them are often conflicting, and they remain very mysterious.
Xenomorphs live in a caste system in hives. Each hive is ruled by a queen. The Xenomorph seeks to reproduce and survive for the future. As such, the majority of its known functions are used not to kill, but impregnate. Xenomorphs reproduce by impregnating other organisms. Once the embryo inside of the host it takes the DNA from it,once it is fully developed and ready for independent life it bursts out of the host. Afterwards, it quickly grows into adulthood (the form most people see it as).