This behavior is similar to that of a facehugger.

The Trilobite soon injected the Engineer with a tube-like organ that implanted an embryo through the Engineer's mouth. The fully-grown Trilobite had multiple tentacle-like appendages and skin that resembled that of a Xenomorph's facehugger. She later returned to witness that, although she had removed the creature from her body, it had grown immensely in size.

It was removed via cesarean before it had fully grown and developed, yet it survived this procedure after Shaw left the area. It originated after Shaw's lover, Charlie Holloway, was infected by the Black Liquid, and passed the mutated Trilobite sperm to Shaw. It developed as an endoparasitoid inside an Engineer host and was implanted inside this host by a creature known as the Trilobite. The Trilobite, in turn, gestated as an abnormal fetus within Elizabeth Shaw's womb, where it grew with frightening speed. The Deacon appears to be a unique creature, though it might conceivably be regarded as the first of a new species. Its skin resembles that of the Xenomorph with an insectoid or reptilian appearance, although the Deacon has a distinct blue tone whereas the others generally have a significantly darker tone with very little color. Instead, it has a more primitive jaw mechanism akin to a goblin shark.

Like the Xenomorphs, it is bipedal with an elongated skull, but it lacks a tail and has no mouth-like tongue. The Deacon's anatomy has many similar features to the Xenomorph, but is very distinct in comparison.

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