“Alien” is a franchise that gave life to and is famous for the alien known as the “Xenomorph.”
The Xenomorph originally was found on the planet LV-426 (also known as Acheron). After some modifications from an android, or as they prefer to be called “synthetic humans,” the Xenomorph was born from an egg produced by a queen Xenomorph almost three times as big as the regular Xenomorph and just as strong.
The Xenomorph comes out of the egg, not when ready to hatch but rather when movement is detected near the egg. The eggs are commonly seen in a thick haze on the ground or near a fresh host.
However, the Alien isn’t a Xenomorph when it’s hatched; in fact the Xenomorph stage is only seen after the full growth of the creature. After it hatches it looks like a large skinny hand with a tail; they have no eyes so they go off of sound and body temperature. The Alien then lunges at the face of any unlucky living creature that’s around giving it the name “face huggers.”
It thus impregnates the host by forcing a tube like body structure down the throat of its host and laying eggs in the chest cavity after rendering the creature unconscious, while pumping oxygen to the lungs of the host. If the face hugger is interrupted while laying eggs, it’s tail will tighten around the host’s throat, and the tail can’t be cut off due to its acidic blood that burns through steel in matter of seconds with no issues.
This is demonstrated in the first movie when one of the crew members of a ship called the “Nostromo” gets face hugged, and the other crew members try to save them by removing the face hugger before the eggs are laid but to no avail.
After the impregnation, the facehugger falls off of the host and dies, leaving the host with a sense of false hope that they are okay.
The symptoms of a Xenomorph impregnation include: sore throat, thirst, hunger chest pain, and rapid expulsion of a Xenomorph in its second stage from the chest. This sage, due to the chest expulsion, is called the chest-burster.
