These are Ostraka (also spelled ostraca) fragments from fifth century B.C. Athens. (Image credit: Shutterstock) "Greeks may have also wiped with ostraka, ceramic pieces that they inscribed with the names of their enemies when voting to ostracize them."
Interviewed again about toilet paper! This time by Live Science for a piece by Tara Santora called "What did people use before toilet paper was invented?" The topic continues to fascinate.