This is why you want to turn the light on before you go, even if you are pretty sure you can see the general outline of the crapper.
Reminds me of what professional African hunter Peter Hathaway Capstick did on a safari. The camp had a brush screened outhouse and someone saw a Black Mamba slither into it.
Capstick went in and found nothing there, even searching everywhere. Nothing was found. A little later, he went back and burned it completely down. He did not want to take a chance with a Black Mamba.