pyx

A small metal box used in the Roman Catholic Church for carrying the Blessed Sacrament to the sick; also a larger receptacle for exposing the host or consecrated bread.

A pyx or pix is a small container used in the Roman Catholic, Old Catholic and Anglican Churches to carry the consecrated host, the Eucharist, to the sick or invalid or those otherwise unable to come to a church building to receive Holy Communion. While the word may be applied to any covered carrier, in the modern usage the term is usually applied to small, flat, clamshell-style containers often about the size of a pocket watch and usually made of brass, traditionally lined with gold.

The term pyx is sometimes also used of the luna or lunette, a flat, circular container composed of a ring of metal (usually lined with gold) holding two glass or crystal disks, to create a round, flat glass-enclosed space for the Eucharistic host. The lunette is often kept in another object sometimes called a pyx, sometimes called a custodia, which is usually a round box often on a small stand, giving the impression of a faceless old-fashioned alarm clock.