Bread Seal from Mount Athos
Prosphora (Greek for "offering") is bread prepared for use in the Divine Liturgy. A portion of it, known as the lamb (or amnon) is cut out during the proskomedia which is consecrated during the Divine Liturgy to be the Eucharist, while the rest is cut up for the antidoron, the blessed bread distributed at the end of the liturgy.
During its preparation, prosphora is stamped with an image usually including IC XC NIKA ("Jesus Christ conquers"), which is maintained during baking and then serves as a guide for cutting out the lamb during the proskomedia.
Prosphora can vary in size and stamp in different traditions. Generally, the Slavic traditions use smaller prosphora with a simpler stamp, while the Byzantine ones use larger ones with a more complex stamp.