The Ovomorph, known colloquially as the Egg, is an egg-like capsule containing a Facehugger, generally considered to be the first stage in the Xenomorph species. They are produced and laid by a Queen.

Xenomorph Eggs by themselves are seemingly inert and are often dismissed as nothing more than lifeless vessels simply designed to contain the Facehugger. However, study has shown that they are in fact complicated organisms in their own right and that they exist in a symbiotic relationship with the Facehugger they contain. They notably possess the ability to "sense" or otherwise detect when a potential host creature approaches, at which point four "petals" at the top of the Egg open up and the Facehugger within launches itself at the nearby victim.