A rare £1 coin that looks like a fried egg due to an error in its design has sold for £257 on eBay. The unusual piece has a misaligned core – which means the silver coloured centre of the pound coin bleeds into the outer ring. All new £1 coins are made with two metal rings – the outside is made from nickel-brass, while the inside is nickel plated brass alloy. The inner circle is supposed to fit perfectly in the centre of the coin but this one is elliptical in shape. Coins that have been made with mistakes on them are called "error coins" and are extremely valuable to collectors. This is because they could be only one of a handful, or one of a kind – so they're hard to find. The seller of this particular error coin says he isn’t aware of any others like this currently in circulation. They said, “Only one known, to me. Searching for errors regularly for 20ish years on a daily basis. Egg errors are relatively common but, this is the only elliptical one I've seen.” It sold for £257.52 exactly, plus £10 express delivery, after attracting 31 bids during a seven-day auction.