I did a research paper about why the octopus is most likely to become the dominant species following our extinction (mostly due to their fascinating brain structure and intelligence, and their incredible tactile versatility of their tentacles in comparison to our primitive meat sausages); and in the process of that research I can tell you almost for certain that the octopus, and other similar cephalopods, first came about when many larger, mollusk like creatures with tentacles, left behind their shells in exchange for far greater mobility. This is all just quack nonsense, the humble, and graceful octopus may be strange, and alien, but they’re no less one of us earthlings. (This guy would probably freak if he found out John Oliver had an entire segment dedicated to praising the Octopus)