ὄστρακον

Etymology
Traditionally held to be related to and. Beekes considers it more likely to be, which does not exclude a relation to.

Noun

 * 1) earthen vessel
 * 2) fragment of such a vessel, potsherd
 * 3) earthen castanet
 * 4) the hard shell of animals such as mollusks and turtles
 * 5) mother of pearl
 * 6) eggshell