we've found the aliens

This article talks about a "Theia water" theory to explain the existence of water on our planet. Scientists have for years surmised that Terra was naturally dry, and that water came from elsewhere, but the original guess was that it came via many strikes from "carbonaceous" meteorites. The new hypothesis is that "Theia" (Gk., goddess)—a planetoid that may have smashed into Terra and formed the moon, as well as adding bulk to our world—may have brought along the earth's water. Fascinating if true.

And the theory has implications: if we humans are composed mostly of water (60% is one common figure), and if all water is extraterrestrial in origin, then that makes us mostly extraterrestrial. We've found the aliens, and they are us.