When the Engineers came to the planet G-435, they found a lush planet teeming with life. But they also saw that the intelligent life there would soon start space exploration. And that would mean a challenge to the Engineers' hegemony over space. They couldn't let that happen. So they sent one of their own on a suicide mission to deliver a genetically engineered bioweapon. That Engineer consumed the bioweapon, releasing it on G-435. As a result, the creatures that lived on G-435 became twisted versions of themselves, optimized killing machines with insatiable appetites. One species, which humans later called Xenomorphs, evolved to be particularly effective—and cruel—killing machines.
But Xenomorphs weren't the only species to emerge from the biological attack on G-435. A synthetic scientist from Earth, named Keri, visited G-435 and catalogued many different kinds of arthropod-like creatures that she called xenostracans (from Greek ξένος xénos "alien" + Greek όστρακον óstrakon "shell"). Here is a sampling of the xenostracans that Keri observed:
After the initial biological attack there were the other semi-sentient races that emerged, but they were all driven to extinction by the Xenomorphs:
And just for fun, a few of the attempts that didn't turn out quite right but that I thought were still worth keeping:
These illustrations were drawn using Stable Diffusion 2.1.
