Today commemorates the stigmata of Saint Francis - the five wounds of Christ miraculously formed in His flesh. These nails could move within the wounds. Here's the account from the Fioretti:
On the death of St Francis his glorious, the sacred stigmata were seen and kissed, not only by the said Lady Jacopa and her company, but by many citizens of Assisi; among others by a knight of great renown, named Jerome, who had doubted much, and disbelieved them; as St Thomas disbelieved the wounds of Christ.
And to assure himself and others, he boldly, in the presence both of the brethren and of seculars, moved the nails in the hands and feet, and strongly pressed the wound in the side. By which means he was enabled to bear constant witness to the truth of the miracle, swearing on the Gospels that he had seen and touched the glorious, holy stigmata of St Francis, the which were seen and touched also by St Clare and her religious, who were present at his burial.
Here is another description of the wounds and their fleshly nails:
For upon his hands and feet began immediately to appear the figures of the nails, as he had seen them on the Body of Christ crucified, who had appeared to him in the likeness of a seraph. And thus the hands and feet appeared pierced through the midst by the nails, the heads whereof were seen outside the flesh in the palms of the hands and the soles of the feet, and the points of the nails stood out at the back of the hands, and the feet in such wise that they appeared to be twisted and bent back upon themselves, and the portion thereof that was bent back upon themselves, and the portion thereof that was bent back or twisted stood out free from the flesh, so that one could put a finger through the same as through a ring; and the heads of the nails were round and black. In like manner, on the right side appeared the image of an unhealed wound, as if made by a lance, and still red and bleeding, from which drops of blood often flowed from the holy breast of St Francis, staining his tunic and his drawers.
Clearly, this stigmata of the Seraphic Father Saint Francis was different from that of Saint Pio of Pietrelcina.