It's been serving as the Stronghold of my matched pair of Battle of Hoth armies for Hordes of the Things for many years. It's made of heavy grade, grey polythene but there's some kind of mechanism inside. There's a LucasFilm copyright notice printed on it somewhere so I guess it is actually from somewhere in the Star Wars canon.
As the picture below shows, there's a rotating section on top and some kind of ratchet mechanism can be heard inside as it moves.
What the hell is this beast?