I'd like to replace an old, rusted light fixture on the bathroom ceiling. Unfortunately, I have no idea how it's actually held up to the ceiling. There are no screws on the sides, but there are holes. When I put my finger in to feel for a screw, it seems to only be insulation. I read that it may be spring-loaded? The whole thing does move; I can spin it counter-clockwise and clockwise, but I'm afraid to keep spinning. Is this how it comes down? Any tips are appreciated!