The 'moon-stone' - Anuradhapura, Sri Lanka.

The 'moon-stone' is shaped like a half-moon. It depicts the progression towards liberation. This it is claimed, was an object very sacred. Some sects of Buddhism when they gained the upper hand, used it as a door-step to denigrate the concepts depicted by it. Look at the image of the dwarfs carrying the steps of the stairway.