Xenomorphs are eusocial life-forms with a caste system ruled over by a Queen.

Their life cycle comprises several distinct stages: they begin their lives as an egg, which hatches a parasitoid larval form known as a facehugger, which then attaches itself to a living host. The facehugger then impregnates the host with an embryo, known as a chestburster, which, after a period of gestation, erupts violently from the host's chest, resulting in the death of the host. The chestburster then matures to an adult phase, shedding its skin and replacing its cells with polarized silicon. Due to horizontal gene transfer during the gestation period, the Alien also takes on some of the basic physical attributes of the host from which it was born.