Ok, so I took the nail, flipped Magnus over (he wasn't too please...lol) and compared it. I think it's from his front right paw. I have to say, since they hate their nails being groomed, I don't grind/cut them as often as I should.
Reading your replies and comparing the nail to his, it looks like it "shed" from the 2nd toe. I will definitely relay this to the vet on Sunday and see what she says. But for now, my mind is at little more ease since it doesn't seem to be something awful like tumor.
Thank you guys!!!!! Will post follow up when I get back from the vet!