Sunstone



A Sun Warrior treasure, the Sunstone is kept hidden inside a room in the Sun Warriors' Ancient City which is supposedly accessible only during a solstice. It is a round, egg-like object which gleams in sunlight due to its impressive golden color. To find it, after entering the room, two people are required to perform the Dancing Dragon form, following the steps of the statues. This will press switches on the floor, causing the pedestal with the Sunstone to rise. When Zuko picked it up, he commented that it felt alive, shortly before a green, glue-like substance was released and he and Aang were trapped in the room. Ham Ghao accused them of stealing it.

Trivia
The fact that Zuko commented that it felt alive, along with its shape, and how Aang calls it a "glowing egg" lead to massive speculation by some fans, who believed the Sunstone could actually be a dragon egg. This theory is also supported by a virtual artifact that can be earned in the game Avatar: Legends of the Arena that's very similar to this object and is called Dragon Egg. The Sunstone didn't appear again, so the theory wasn't proven either way.