On the J'nanin Age, there are a variety of posts, each with a sort of lens. You must find the source of light (near the yellow post) and turn the cover until the light is directed to the yellow post. From there, point the light from post to post and ultimately to the receptor next to one of the three tusks. The light posts can be manipulated by selecting the ring under the lens. Record the order of the colors of the posts that the light travels to in order to reach the receptor, this order is the key to open the door.