He could of gotten nibbled on after he died. How long has he been dead? I dont know how aggressive water cows are, but tea cup rays are pushovers, and I couldnt imagine a pleco killing a clown knife.
How big were the fish involved ? It's next to impossible to say unless u saw it happen, and dont assume it was a tankmate just because of bites, it's just as likely that is died first and then other fish chewed on it.
If his head was eaten id bet on the ray. They tend to do that. The pleco likely grazed on his dead carcass and the water cow may have caused the death. Really impossible to know for sure
WHO COULD IT HAVE BEEN?
