I've read the Necronomicon*, The one where it has some supre dark god as Murdak or something. It doesn't correspond to the bible. It was Fake, just like the Mad Arab. (Also with all those cut-out bits, I can't help but imagine you with a pop-out children's book that was inspired by a chibi horror style, based of HP Lovecraft's work.) Yet if it does correspond to the bible (If it was ever revised, which is likely because it was a terrible book even for magick's low standards.) It was likely to be manipulated to look like that to make it appear relevant in it's less than hundred years of publication.
However if the Goat kid is real then there is a cause for it looking like that, and I can almost gurantee** that the answer is not going to be aliens, but more likely to be a genetic disorder, or pollution or poisons affects it while it was in the womb. (If you look up Harlequin Syndrome, you'll see a human that has one layer of sub-dermal layers harden into scales, due to a genetic disorder, however causes a negative reaction due to it's 'unsightly' appearance, primarily because it looks like it's eyes are bleeding. However this serves as an example of how much a gene configuration can 'deform' something. As for the poison explanation, Mercury, lead or thallium based compounds all can cause birth defects, Thalidomide was one example for it's able to cause Phocomelia syndrome, as it was once marketed as a morning sickeness pill.)
*Years ago, when I was in Holland.
**The odds of Aliens existing as they do in popular opinion is quite unlikely, although I'm not too skeptical about micro-biotic life on other planets that have traces of water.
Beep Beep, Crime Scene Cleaning in place. ^_^
This isn't the body you're looking for. ;3