"Tamata are the symbols of the miracle of healing which is hoped to occur, or has already occurred. They are the vehicle in which we invest our faith. So they are an integral part of the miracle. Tamata are a link between the person and the Holy spirit.
Tamata made of clay have been found at ancient Greek healing centres and temples, such as religious sites of the Prepalatial Bronze Age around 3,000 BC, on Crete . They have also been found at 8th century BC sites, such as at Amphiarion where the majority were still made of pottery and wood, but also metal ones started to appear. "
-BY ADRIAN VRETTOS
http://www.athensguide.com/journalists/articles/tamata.htm