One of the deadliest of all known alien species, these creatures require a host organism in order to reproduce. The appearance of the Xenomorph can vary depending on the host in which the embryo is implanted. The Human phenotype is generally around 7–9 feet in height and roughly 400-600 pounds in weight, with a long, muscular tail and large, curved, oblong head. The Queen of this species is generally twice as large (although some Queens have been shown to grow even larger, some surpassing 30 meters in height if given time) and possesses superior speed, strength and intelligence compared to her common offspring.