With a hefty kick you send the urn crashing down, away from the others. What spills out across the floor resembles molten lava more than it does silver coins, some kind of liquid fire protected by an illusion. An ingenious little trap.
The stuff pools out on the floor and then starts spreading towards you. Worried, you hop up and sit on the lip of the tomb, but it quickly cools and hardens, forming a layer of igneous rock on one side of the room, though of what type you cannot tell.