Ostraka

An ostracon (Greek: ὄστρακον ostrakon, plural ὄστρακα ostraka) is a piece of pottery, usually broken off from a vase or other earthenware vessel. In an archaeological or epigraphical context, ostraca refer to sherds or even small pieces of stone that have writing scratched into them. Usually these are considered to have been broken off before the writing was added; ancient people used the cheap, plentiful, and durable broken pieces of pottery around them as a convenient medium to write on for a wide variety of purposes, mostly very short inscriptions, but in some cases very long.