See that pig? It used to be a sheep. Even if the sheep there died (which I’m not sure how it would have), the chances of a pig spawning in the exact same place seem pretty remote. I’m not complaining, I wasn’t attached to the sheep, but I just thought I’d mention it, since it’s awfully weird.

Its very obvious what’s happened here. Your base is filled with angry demons and they killed the sheep and put a pig there. I’d suggest paying Jack the low low price of 100 stacks of diamond blocks to get rid of them for you.