It’s worth remembering that “Alien” is rife with genital imagery, mostly taken from H.R. Giger’s works. Giger’s paintings tended to blend the mechanical and the organic, often envisioning a post-apocalyptic hell wherein human-like figures were still beholden to sexual impulses, but whose bodies had been partially absorbed into ineffable, tube-sprouting contraptions. Indeed, the design for the Xenomorph itself comes from a painting called “Necronom IV,” wherein a human-shaped figure sported a skull that was extending backward into a massive phallus. The creature’s own phallus was large enough to extend upward over its own head. The movie Xenomorph was, not to put too fine a point on it, a penis monster.
It would aesthetically follow, then, that the alien eggs should also feature genital features. Giger designed a vulval opening in the top of the egg, further expressing his own genital-heavy interests. When that idea was rejected, Giger pivoted to the “cross shape” as an impish piece of satire; if the filmmakers were going to be puritanical about genital imagery, then he’d provide a Christian design to placate the prudes. Roger Christian said it thus:
“The first ones he did looked much more like a woman’s private parts, and the producers all worried. […] Giger said, ‘Well, if it’s a cross, then it’s religious, and people don’t worry about that.'”
The final design of the egg isn’t so much Christian as it is cardiovascular; the four-flapped egg opening looks like an outsize heart valve. It may have been Giger’s sneaky Christian “prank,” however, that would inform director Ridley Scott when he made his prequel film “Prometheus” in 2012.
