Trilobite (Prometheus)

The Trilobite is a creature derived from the Black Liquid of the Mala'kak.

The liquid, when ingested by Dr. Holloway, spreads through his system within a 24 hour period. Before realizing the changes taking place in his body he and Dr. Shaw had intercourse whereby transmitting some of the changed DNA to her in the form of sperm. She soon became pregnant. However,the rapidly growing alien inside her she had it surgically removed via an advanced medical device on the starship, Prometheus. The creature, presumably dead, appears again at the end of the movie resembling a massive facehugger which grapples with and impregnantes the Mala'kak with a xenomorph like species, the Deacon(termed "Proto Alien" by several online references).