irish coins

I don't think there are 20-euro coins in general circulation in any country. I've only seen up to 2 euros. Perhaps there is a commemorative coin with the design you describe.

Sounds like your friend is having a joke on you.
Coins in all countries using the Euro are 1c, 2c, 5c, 10c, 20c, 50c, €1 and €2. Banknotes are €5, €10, €20, €50, €100, €200 and €500. There is no €20 coin.
Coins have a "common side", which is always the same, and a "national side" which shows the country it was minted in. All Irish Euro coins have an Irish harp on the national side. But, all Euro coins from all countries are valid in all countries using the Euro. In practice you get a mixture of coins from different countries in your change.

Pictures of all the Irish Euro coins are here: https://www.ecb.europa.eu/euro/coins/html/ie.en.html
This is the official ECB (European Central Bank) website.

Each country using the Euro as currency has permission to issue commemorative coins in whatever denominations they choose that don't line up with the regular circulated coinage. They are limited in manufacture, usually of silver or gold, stamped with a proof finish, and I doubt you would be able to spend one if you wanted since shopkeepers wouldn't know what to do with it in their till.

You are describing a coin Ireland issued in 2007. The real coin was real gold, so I don't think it would be made into a fridge magnet!

Here is a picture and description of it: http://talismancoins.com/products/99957

I don't know for sure, but it looks to me that it might be an open book, maybe representing the illuminated manuscripts that the Irish monks used to create, especially the Book of Kells in Dublin. Just a guess.

Reminds me of the old "Scottish Passport". Among other things, you got a stamp for eating haggis.

Thanks everyone. Mark has the answer. I checked the site and there it was. Of course mine is just a replica made into a magnet but at least now I know what it is. Thanks again. shk