I'm currently playing Twilight Forest on a FTB server running version 1.12 of the Direwolf20 modpack. While exploring the forest I found this MASSIVE mushroom castle in a biome called Lots of Mushrooms. It's definitely naturally generated, and I couldn't find any mobs or anything inside it (except for some rams that spawned on the roof).
Like I said, I couldn't find any information about this anywhere... so I guess what I'm asking is... what is this structure? And are there any mobs or bosses planned for it in the future?