You don't have to be on an 'eye-spy' mission in Glasgow to notice the city's distinctive coat of arms.

It is all over the place, on the sides of buildings, on clock towers, gates, lampposts, even rubbish bins.

The one pictured is visible as you walk along the River Kelvin footpath. It is built into the bridge that crosses the river at Gibson Street.

The design - with the city motto Let Glasgow Flourish - is depicted on the crest of institutions including Glasgow University and of course Glasgow City Council.

Its component parts are three fish, each with a ring in its mouth; an oak tree with a bird at the top and a bell hanging from its branches; a crown; the city's patron saint St Mungo at the top; and the motto Let Glasgow Flourish emblazoned along the bottom.

There are a number of intriguing tales and legends associated with it, all dating back to the days of St Mungo who lived in the 6th century.

Most Glaswegians will have at least a passing familiarity with the saying:

There's the tree that never grew,

There's the bird that never flew,

There's the fish that never swam,

There's the bell that never rang.

So let's break them down so they can be properly explained.

* The young Mungo was charged with ensuring that a goblet at St Serf's monastery on the banks of the Forth. When rivals put out the holy fire, Mungo blew on a hazel branch which burst into flames and re-ignited the fire. (hence the tree that never grew)

* A wild robin was tamed by the head of the monastery. When the bird died, Mungo prayed over it and the bird was brought back to life. (the bird that never flew)

* The fish is the most intriguing. A queen of Strathclyde was having an affair with one of her husband's knights and when the king found out he threw his wife's ring into the river then demanded that she return it to him. She begged Mungo to help her and he cauight a salmon from the river, opened it up and there was the ring. Not just a miracle but a saint's collusion with an extra-marital affair? (the fish that never swam)

* In 1450 John Stewart, the city's first Lord Provost, left an endowment for a St Mungo's Bell so that citizens could pray for the saint's soul. (the bell that never rang)

One of Mungo's early sermons contained the words "Lord, let Glasgow Flourish by the preaching of the word" and the shortened version - Let Glasgow Flourish - remains the city's motto to this day.

So next time you pass a coat of arms, bear all that in mind.