http://agathe.gr/democracy/the_jury.html
The Jury The jurors for each trial were chosen from a large body of citizens available for jury duty for the period of one year. At the beginning of the year, each juror was given a bronze pinakion, a ... According to Aristotle, the juror on entering the court received a token, or symbolon (Athenian Constitution 65, 68, 69). ... Payment was made only at the end of the trial and only upon presentation of the symbolon. Numerous symbola have been found scattered over the Agora; they carry different devices and letters to indicate the court to which the juror was assigned.