Situation: I am working at a desk. There are a group of desks behind me and a bookshelf in my 8 o'clock direction. There is a desk on my right, too.
Alternative situations: I did a study session for my test at the desk and behind me were two other desks. I am sitting in a cubicle on the left side of the room, a chair is behind me, I am listening to music while my forearms are resting on the desk.
Question: What is under the desk behind me?