Well, now we can say with certainty that not all the 'monster stories' we hear are false. I am talking about Season 10 Episode Three 1 Feb. 2016 "Mulder & Scully Meet the Were-Monster".
There were no scientific explanations for the lizard looking man like thing which turned into a man and back to a monster several times during this documentary episode. The dang thing really is a kind of monster, from our perspective. ("Gary" views us as monsters of course. He witnessed a murder or two, committed by a human, so he is a little leary about our species.) Of course, it is hard to prove that he exists now. He went into hiding for a ten thousand year hybernation period, starting last year, so we will have to wait Nine thousand, nine hundred, ninety-nine years til he wakes up in order to see and talk to him again. I doubt I will still be alive then. I am sure glad I got a chance to see him this time around. Luckily there were cameras there to record him changing into a monster mid-handshake with Mulder, and you can still see it during reruns or on DVD.