Humanity has, over time, moved species across continents as we migrate. Scientists have warned that Alien organisms could reach Earth through our own crafts exploring outer space. It is most likely that any invasive species met on an alien planet would be microbial and resemble bacteria on Earth. While the the likelihood of any extraterrestrial life form making the trip through space is very low due to the harsh conditions of interstellar travel. What powers does the Aliens Have ?