Well, that was weird

I just went out to make sure the girls were all tucked in for the night, opened up one of the side doors and found...a possum. I have no idea how it got in there, and it's too dark to figure it out. Chickens are all fine. I caught it and it's stuck under a bucket with a 20 pound bag of salt on top. I'm hoping it freezes overnight, otherwise, I have no idea what to do with it.
That wasn't what I expected when I went out there...