It opens up to reveal another, smaller, chest. That one then opened to reveal another chest, which then opened to reveal another. This continued for several moments before finally, after three more chests, the last one opened to reveal the compartment within. Slowly, and with a great deal of trepidation, all three Professors and Harry approached. When they were close enough they peered down, looking through the magical pit contained within the chest to find one Alastor Moody sitting below. 