Construction workers removing a century-old copper cross from a church in Buffalo, N.Y., discovered letters written by Catholic schoolchildren concealed inside. Over the years, exposed to temperature changes and water, the letters had mostly congealed into unreadable lumps, The Buffalo News reported Thursday. There were holy medals and one still readable calling card. Corpus Christi parish plans to replace the letters with new ones when a new copper cupola and cross are put up. Some of the old ones will join them. Rev. Mariusz Dymek, administrator of the parish, said concealing letters and written prayers in a church building has a long history dating back to the Middle Ages. \"You build buildings from brick and stone,\" Dymek said. \"But this is spiritual brick.\" The parish was founded in 1898 to serve the immigrants then flooding into Buffalo. The church was completed a few years later. Corpus Christi in its heyday had a convent with more than 100 nuns, most of them teachers serving a large parochial school. The school closed in the 1980s. The letters hidden in the cross had been part of the parish tradition.