You go back to the locked door in the room with the glowing mushroom. Gerald inserts the goblin bracelet into the door's hole. The pins grip it, retract, and the door swings open.
A huge golden statue of a snake-headed humanoid with its arms crossed over its chest stands at the center of a large room. At the statue's base is a big pile of gold coins. On the other side of the room is another door with a bracelet sized hole.