Reliquary theca with relic of St. Joseph Calasanz, founder of the Pious Schools

Oval glass-fronted brass pendant reliquary theca housing first-class Ex Praecordis (of the inner organs) relic of Saint ​Joseph Calasanz. A relic is affixed to a gilt paper burst on a silk ground, surrounded by silver wire ornamentation, and identified in Latin on a fancy manuscript cedula label as Ex Praecord. S. Joseph. Cal. (of the inner organs of Saint ​Joseph Calasanz). On the back, the theca is secured with a perfectly preserved seal of red Spanish wax bearing an imprint of a coat of arms of Fr. Francesco Maria Ginori (†1775), Bishop of Fiesole, Italy (1736–1775).

Saint ​Joseph Calasanz, Sch.P. (Spanish: José de Calasanz; Italian: Giuseppe Calasanzio), (†1648), also known as Joseph Calasanctius and Josephus a Matre Dei, was a Spanish Catholic priest, educator and the founder of the Pious Schools, providing free education to the sons of the poor, and the Religious Order that ran them, commonly known as the Piarists. He was beatified on ​in 1748, by Pope Benedict XIV​ and canonized by Pope Clement XIII ​in​ 1767. On August 13, 1948, Pope Pius XII declared him to be the "Universal Patron of all Christian popular schools in the world." His feast day is celebrated on August 25.