X-525652 was a breakthrough for the X-files, and for the way we see the paranormal. Although at the time Arthur Dales wasn't ready for what was ahead of him, and, inevitably, will result in the end of his career. This was because the X-files were simply cases deemed unsolvable at the time, and the reason why it was listed under "x" is not because it sounds, mysterious, but because that was the only letter left to categorize it under, or at least that's what the episode said.
Arthur Dales thought he would have crack at these "unsolvable" cases. The case started like a normal case with Edward Skur a family man, arrested for murder, and ended with, Edward Skur a man with a spider like extraterrestrial predator that lives inside his mouth, that preys on human beings by sucking out their insides, to read more about it click on the link on Edward Skur. Later Arthur Dales did eventually make a report on Edward Skur and the X-file behind it.