Walk through the Christian quarter of Jerusalem's Old City and you'll see souvenir shops selling assorted varieties of small plastic Christian prayer boxes displaying miniature icons, usually Mary and Jesus, surrounded by a gold halo. Not far from those shops, Israeli archaeologists have discovered what may be the oldest miniature Byzantine prayer box to date, archaeologist Yana Tchekhanovets announced last week.

The discovery - made by Tchekhanovets and fellow archaeologist Doron Ben-Ami about a year ago during an Israel Antiquities Authority excavation in the Givati parking lot across from the City of David - sheds light on art in ritual in Byzantine-era Jerusalem.

The box, discovered in the Byzantine strata (324-838 C.E.) in the plaster between two floor tiles, is approximately half the size of a matchbox: 2.2 centimeters by 1.6 centimeters, and a few millimeters high. The inside contains delicate and partially erased drawings of Christian icons. With a little effort it is possible to discern a blurred feminine face and, on the bottom, a clearer male face. The colors used to make the icons have survived and shades of red, blue, brown and white are detectable, all against a delicate gold background.

"Never before have we held such an object in hand," said Tchekhanovets, who announced the discovery at an archaeology conference held at the Hebrew University of Jerusalem, in conjunction with the Israel Antiquities Authority. "It's very exciting that we uncovered it," she said.

The big question revolves around the identity of the two icons in the prayer box. The likely answer, says Tchekhanovets, is that they are Jesus and Mary, but it is certainly possible that they could be other local saints who flourished in that era. Like the prayer boxes sold today in souvenir shops, its Byzantine predecessor was used as a personal ritual object that could be taken anywhere. When worshipers wanted to pray, they would open the box and pray before the icons, and it would function as a miniature church.

The archaeologists have handed over the prayer box to the Hebrew University's nanotechnology lab for further review, providing additional information about the composition of the pigments used on the prayer box. Of the two substances used as the base for dyes in that period, beeswax and egg yolks, Tchekhanovets believes that the eggs were preferred by the artist who drew these icons.

This is not the first ancient prayer box to be discovered in the region.

The cover of a similar, and perhaps identical, box - but not the images inside - were found in the Jordanian city of Jerash many years ago, indicating that the prayer box discovered in a modern-day parking lot in Jerusalem is not the only one of its kind.

"If we found two objects, one in Jerusalem and one in Jordan, presumably there were also several dozen more of them," said Tchekhanovets.