Hammerpede

The Hammerpede is a worm-like creature seen in the movie Prometheus.

Not much is known about this lifeform, not even its origin. Its assumed that it may either be a native lifeform of LV-223 or was brought there by the Space Jockeys.

It may perhaps have been a bio-weapon used by the Space Jockeys or some kind of an experiment, a genetic mutation experiment that went wrong.

As seen in the movie, it is safe to say that the Hammerpede is aggressive as it would attack any living creature that was nearby. When it detects a host, it will approach and attack by wrapping around the prey's arm (it is believed that the Hammerpede appears to be extremely strong, strong enough to coild around a man's arm and possibly breaking it). And similarity much like the Xenomorphs, the Hammerpede has acid for blood.

The Hammerpede's size is no more than a snake size and its appearance is almost similar to a cobra. The Hammerpede lacks eyes, and how it detects its prey is a mystery, perhaps it "sees" through movement or heat signature. How the Hammerpede attacks its prey is by moving with an exceeding speed, it attaches itself to the victim's arm (as seen in the movie), then goes down the throat of the host, presumably killing the host by suffication. The way it attacks may resemblance the Facehugger, however it is unknown if it whether impregnate its victim or just feasting on the victim's inside is pretty unknown.

It could be one of the stages of the Proto-Xeno, seen at the end of Prometheus, but it's not confirmed.