pyx -
The small container used to hold the consecrated bread of the Eucharist.
Wikipedia
A pyx or pix is a small round container used in the Catholic, Old Catholic and Anglican Churches to carry the consecrated host, to the sick or invalid or those otherwise unable to come to a church in order to receive Holy Communion. The term can also used in archaeology and art history to describe small round lidded boxes designed for any purpose from antiquity or the Middle Ages, such as those used to hold coins for the Trial of the Pyx in England.
