The moonstone is a semi-circular slab of granite or limestone. This is usually the first in a flight of steps. It is richly designed in concentric (with the same centre) semi-circular bands of carvings of flowers, creepers, birds and animals.
The moonstone is a permanent feature of the buddhist building of all historical periods. This is a semi circular piece of stone which stood at the foot of a flight of steps in most buddhist buildings. Although the moonstone is generally semi circular, Sometimes you can come across square moonstones. It is thought that the moon stones originated as blank square stone and later developed in to a semi circular shape.