Saint Aubert was bishop of Avranches in the 8th century and is credited with founding Mont Saint Michel.

He lived in France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 during the reign of Childebert III

Childebert III

Childebert III, called the Just , son of Theuderic III and Clotilda and sole king of the Franks , he was seemingly but a puppet of the mayor of the palace, Pepin of Heristal, though his placita show him making judicial decisions of his own will, even against the Arnulfing clan...

 (695-711) and died in 720. According to legend, in 708 he had a vision in which the Archangel Michael instructed him to build an oratory

Oratory (worship)

An oratory is a Christian room for prayer, from the Latin orare, to pray.-Catholic church:In the Roman Catholic Church, an oratory is a structure other than a parish church, set aside by ecclesiastical authority for prayer and the celebration of Mass...

 on the rocky tidal island

Tidal island

A tidal island is a piece of land that is connected to the mainland by a natural or man-made causeway that is exposed at low tide and submerged at high tide. Because of the mystique surrounding tidal islands many of them have been sites of religious worship, such as Mont Saint Michel with its...

 at the mouth of the Couesnon

Couesnon

The Couesnon River is a river running from the département of Mayenne in north-western France, forming an estuary at Mont Saint-Michel. Its final stretch forms the border between the historical duchies of Normandy and Brittany...

. Aubert did not pay attention to this vision at first, until in exasperation Michael appeared to him again, this time driving his finger into Aubert's skull and ordering him to complete the task again. Michael is said to have appeared to him a total of three times. After this the oratory was built. It was dedicated on October 16, 709, and Aubert is reputed to have been buried in it.

The relic

Relic

In religion, a relic is a part of the body of a saint or a venerated person, or else another type of ancient religious object, carefully preserved for purposes of veneration or as a tangible memorial...

 of Aubert's skull, complete with hole where the archangel's finger pierced it, can still be seen at the Saint-Gervais Basilica in Avranches

Avranches

Avranches is a commune in the Manche department in the Basse-Normandie region in north-western France. It is a sub-prefecture of the department. The inhabitants are called Avranchinais.-History:...

. It is more generally believed nowadays that the skull is in fact a prehistoric relic showing evidence of trepanation

Trepanation

Trepanning, also known as trephination, trephining or making a burr hole, is a surgical intervention in which a hole is drilled or scraped into the human skull, exposing the dura mater in order to treat health problems related to intracranial diseases. It may also refer to any "burr" hole created...

. He is regarded as a saint

Saint

A saint is a holy person. In various religions, saints are people who are believed to have exceptional holiness.In Christian usage, "saint" refers to any believer who is "in Christ", and in whom Christ dwells, whether in heaven or in earth...

 in the Roman Catholic Church

Roman Catholic Church

The Catholic Church, also known as the Roman Catholic Church, is the world's largest Christian church, with over a billion members. Led by the Pope, it defines its mission as spreading the gospel of Jesus Christ, administering the sacraments and exercising charity...

, with a feast day of September 10.