Jiaobei

Moon blocks or jiaobei (also written as "jiao bei" etc variants; ), also poe (from ; as used in the term ""poe" divination"), are wooden divination tools originating from China, which are used in pairs and thrown to answer a yes or no question. They are made out of wood or bamboo and carved into a crescent shape. A pair of clam shells can also be used. Each block is round on one side (known as the "yin" side) and flat on the other (known as the "yang" side). It is one of the more commonly used items found in Chinese traditional religion and are used in temples and home shrines along with fortune sticks, both of which are often used together when requesting an answer from the gods.
Practice.
Moon blocks can be used separately to receive a straightforward answer, or they are accompanied by fortune sticks to clarify an oracle. When used alone, moon blocks are first purified by revolving the blocks around the incense burner three times. The querent then kneels and says their name, date of birth, residence, and question while cupping the blocks between their hands in prayer. After the querent poses the question to the gods, the blocks are dropped to the floor and land in a specific position. 
There are four possible answers that the moon blocks can produce:
When used alone without the fortune sticks, the blocks are thrown three times in order to maintain accuracy of the deity's answer, a successful answer usually being three consecutive throws showing "shèngjiǎo", or best two out of three throws.
Usages.
Aside from questioning the deities on mundane affairs, moon blocks are also used to verify a range of issues, such as proper ritual protocol, spiritual presence of the gods or if they have eaten the offerings presented to them.