This is a carved selenite dish. It is carved into the the phases of the moon, waning, full and waxing moon. It is great for Earth centered ceremonies that also involve the moon.  

(US Imperial Ruler in pictures for scale)

Each stone and crystal has metaphysical properties that can help aid in specific situations, help boost certain body functions/body parts, and can even offer different insight into the seen and unseen world around us.

Selenite: Is a very powerful healing and cleansing stone. If one spends enough time with it, one’s mind will open up and become far more clear. It is said to help relax and bring peace to those with scattered minds. Selenite is a great meditation stone. It helps one push farther into the cosmos and heavens while meditating. It also helps one come back safely from deep meditations. This is also a manifestation stone. It will help one find what one wants most in life.