Round glass-fronted silver reliquary theca dating to 1920's housing first class ex ossibus (from the bone) relics of Saint Didacus of Alcalá, (Diego de San Nicolás). The relics are affixed to a red silk background and identified on a typographic cedula as S. Didaci C. (Saint Didacus, Confessor). On the back, under a protective cap, the theca is protected by a seal of red wax with a hardly visible imprint of a coat of arms of the Order of Friars Minor Capuchin sealed by Fr. Anthony M. Santarelli, Postulator General of the Order in 1920's responsible for a cause for beatification and canonization through the judicial processes required by the Roman Catholic Church.
Didacus of Alcalá (†1463), also known as Diego de San Nicolás, was a Spanish Franciscan lay brother who served as among the first group of missionaries to the newly conquered Canary Islands. Didacus was canonized by Pope Sixtus V in 1588, the first of a lay brother of the Order of Friars Minor. His feast day is celebrated on 13 November and he is the holy patron of the Roman Catholic Diocese of San Diego, city of San Diego, and lay brothers of the Order of Friars Minors.