Xenomorph Life Cycle

The life cycle of a Xenomorph is a complex process involving several distinct stages and the use of a living host organism (which can be used only in adult xenomorphs, not all sapient species) as a vessel inside which the infant Xenomorph gestates. The cycle, and in particular the use of an adult Xenomorph (which can be a host for a facehugger) that invariably perish when the infant Chestburster forces its way through their ribcage, is often considered the species' signature aspect and is the characteristic for which they are most well known.

Here in real life (or the Novum Terram universe), the life cycle of a Xenomorph is now much better and more safer that what it is in the Alien universe. So, instead of facehuggers coming to trap the faces of all sapient species that are not Xenomorphs, and chestbursters bursting to the chests of all sapient species that are not Xenomorphs, they instead use eggs (or ovomorphs) to have facehuggers trap the faces of adult Xenomorphs, and then, to have Chestbursters burst into their chests, and instead of one, due to the lack of breeding, it'll be averagly one or two Chestbursters to burst out from an adult Xenomorph.