This reminded me of the time the (extremely fun) church organist played "O Sacred Head Now Wounded" as incidental music on the Festival of the Circumcision.
Researching for my upcoming trip to Rome, and discovered that one of the relics once held in the Santa Sanctorum (or Holy of Holies) at the top of the Holy Stairs outside of the Lateran Palace was (wait for it)…. Jesus’s foreskin. Also, some of Mary’s dried breastmilk.