There have been three sets of coins in Ireland since independence. In all three, the coin showed a Celtic harp on the obverse. The pre-decimal coins of the Irish pound had realistic animals on the reverse; the decimal coins retained some of these but featured ornamental birds on the lower denominations; and the euro coins used the common design of the euro currencies. The pre-decimal and original decimal coins were of the same dimensions as the same-denomination British coins, as the Irish pound was in currency union with the British pound sterling. British coins were widely accepted in Ireland, and conversely to a lesser extent. In 1979 Ireland joined the Exchange Rate Mechanism and the Irish pound left parity with sterling; coin designs introduced after this differed between the two countries.