They do this a lot in Krokotopia. They use clues to finish parts of a quest.
When you enter the room, there are yellow banners hanging of the wall. Look at what is on each banner. Then go and light up each obelisk in the room to match what was on the banners. I forget if there are 3 or 4 banners. After you light the obelisks, the chest appears in the room.
In case the banners fade away before you get to see what is on them, just back up and leave the room, and come back in again. The banners will reappear.