Last night my wife and I had 3 Fulings spawn inside our base. I have no idea how they managed it.

The base is surrounded by a moat and then a stone wall. The entire base including the walls and the moat are all covered by workbenches. We haven't had anything spawn inside this base since I first surrounded it with a wooden fence way back around the time of killing the Elder and we are now trying to find the Queen in the Mistlands. I even walked the base after the attack checking for any gaps in workbench protection only to find none.

It was interesting and somewhat perplexing but was at night. Neither of us died and the Fulings donated to our gold and black metal stocks.