Those same pottery shards were used to cast votes to exclude undesirables from a community, and is from whence we get the word, "ostracize."
That was an odd, and anti-democratic, and rather stupid practice in Athens. There was just a subthread discussion about it the other day, danged if I can find it. So, instead, an ostraca-related topic from yesteryear:
Trash Talk [ Monte Testaccio, imperial Roman landfill ]
Archaeology, Volume 62 Number 2 | March/April 2009 | Jarrett A. Lobell
Posted on 5/5/2012 11:34:47 PM by SunkenCiv
http://www.freerepublic.com/focus/chat/2880425/posts