Topic summary
Ostraca

Extracted from the Wikipedia article Ostracon.
Egyptian limestone and potsherd ostraca
Anything with a smooth surface could be used as a writing surface. Generally discarded material, ostraca were cheap, readily available, and therefore frequently used for writings of an ephemeral nature such as messages, prescriptions, receipts, students' exercises, and notes. Pottery sherds, limestone flakes, and thin fragments of other stone types were used, but limestone sherds, being flaky and of a lighter colour, were most common. Ostraca were typically small, covered with just a few words or a small picture drawn in ink; but the tomb of the craftsman Sennedjem at Deir el Medina contained an enormous ostracon inscribed with the Story of Sinuhe.