At first, the sea was formed around 5.6 million years ago, due to a large-scale flood, but the waters were separated from the Atlantic Ocean by the Strait of Gibraltar, so, in the hundreds of thousands of years that followed, the water spreads dried out almost completely.
The Irish Punt was legal tender in the Republic of Ireland until 2002, when Ireland joined the Euro. This guide outlines the sources for historical exchange rates between the Irish Punt and Pound Sterling. The Irish Punt established by the Currency Act 1927 had a fixed link with Pound Sterling until March 1979.
These coins were successful from the outset, the sole exception being the half centavo. For reasons which remain unclear, it was rejected by the public, and its coinage for circulation ceased after 1904. As with the other denominations, proofs were struck 1903-06 and again in 1908.