Ultraterrestrials are like extraterrestrials, a very technologically and scientifically advanced civilization (much more so than ours), except they don't come from space but rather, from our own Earth. In fact, they have been living among us since the dawn of time. They may be either a different branch of biological evolution, or a certain human culture that, for some reason, evolved much faster than others. The term was coined by John Keel in the 1970s to explain, for example, the mystery airships.