In both the bathrooms in my house there is a lowered ceiling over the shower and tub, respectively. There's no ductwork running through these areas that I can tell, since there's no vents on any side of it. (All our vents are in or near the floor, and we only have one ceiling return and it's in the hallway.) When I knock on the bottom side of it (i.e. the "ceiling" side) it sounds like sheet metal with a hollow space above. Why is this here? If I remodel at some point in the future, could I remove it and get a higher ceiling over my shower and tub areas? Is there a good reason why I shouldn't remove it? House is a late 1970s ranch located in the Midwest, in case that's relevant.