H.R. Giger’s original Xenomorph Lifecycle.
Mural portrait within the main chamber Set of the Engineer’s Temple (Outpost) in Prometheus.
Giger’s original concept shows the Black Gloop, Hammerpede (worm), Trilobite (Squid), Egg, Facehugger, Xenomorph and a host Engineer. Black Goo canister, Xeno and Facehugger (bottom left & right) depicted in mural in Prometheus.
More questions than answers, so let’s just go with that old classic, “Nature finds away” shall we?