Myth or fact?

I snapped this in Glasgow today. It depicts the story of Glasgow and St Mungo and is found in lots of coats of arm around the place. In the 'Life of Saint Mungo', he performed four miracles in Glasgow.

The following verse is used to remember Mungo's four miracles*:

Here is the bird that never flew
Here is the tree that never grew
Here is the bell that never rang
Here is the fish that never swam

The verses refer to the following:

The Bird — Mungo restored life to a robin, that had been killed by some of his classmates.[6]

The Tree — Mungo had been left in charge of a fire in Saint Serf's monastery. He fell asleep and the fire went out. Taking branches from a tree, he restarted the fire.

The Bell — the bell is thought to have been brought by Mungo from Rome. It was said to have been used in services and to mourn the deceased. The original bell no longer exists, and a replacement, created in the 1640s, is now on display in Glasgow.

The Fish — refers to the story about Queen Languoreth of Strathclyde who was suspected of infidelity by her husband. King Riderch demanded to see her ring, which he claimed she had given to her lover. In reality the King had thrown it into the River Clyde. Faced with execution she appealed for help to Mungo, who ordered a messenger to catch a fish in the river. On opening the fish, the ring was miraculously found inside, which allowed the Queen to clear her name.

*thanks Wikipedia :)