This is an item that is basically a magical lock to a nearby secret and impenetrable door. It’s a way to sneak an interesting puzzle into the game, basically.
In an otherwise empty room is a long, anvil-like piece of stone. The top is flat, and inscribed on the left half of the top are a sequence of figures. To the right of those figures is a small bowl filled with sand. The sand is level and unmarked.
Nothing bad happens if the sand is disturbed, and the sand can be returned to a state of “clean slate”, simply by flattening the sand. The “anvil” is stuck to the ground, and is immovable.
There is a nearby secret door that is found but can’t seem to be opened. The only thing in the room is this anvil-like thing with the figures on it.
The sequence looks like this(I hope the link works, cut and paste if you have to):
(Feel free to download and use that image if you want.)
Once the appropriate next symbol is scribed in the sand, the secret door pops open. Can you figure out the next symbol?
ANSWER: Draw two 8’s next to each other, like this 88. The symbols in the diagram are mirror imaged numbers from 1 through 7.