A receptacle for such sacred objects as pieces of the true cross, short-ribs of the saints, the ears of Balaam's ass, the lung of the cock that called Peter to repentance and so forth. Reliquaries are commonly of metal, and provided with a lock to prevent the contents from coming out and performing miracles at unseasonable times. A feather from the wing of the Angel of the Annunciation once escaped during a sermon in Saint Peter's and so tickled the noses of the congregation that they woke and sneezed with great vehemence three times each. It is related in the 'Gesta Sanctorum' that a sacristan in the Canterbury cathedral surprised the head of Saint Dennis in the library. Reprimanded by its stern custodian, it explained that it was seeking a body of doctrine. This unseemly levity so raged the diocesan that the offender was publicly anathematized, thrown into the Stour and replaced by another head of Saint Dennis, brought from Rome.