Ostrakon

An ostrakon is a piece of pottery, usually a fragment of a pot. They were frequently used as a medium for writing. In ancient Athens, they were used for the casting of votes, and decisions to exile or ostracise individuals were made by citizens writing names on ostraka. The fragments of this ostrakon, dating from first or second-century Roman Egypt, contain a horoscope.

Ostr. Sup. 236