A trusted friend who helped them transform their country from postwar devastation to an economic powerhouse, the Germans found it hard to part with the deutsche mark. Four years after saying good-bye, many of them still calculate euro prices back into the mark to get a feeling for how cheap or expensive something is.

Around 15 billion D-marks -- half notes and half coins -- were in circulation by the end of 2005, said Uwe Deichert, a spokesman for the Bundesbank, Germany's central bank. That's about 7.5 billion euros ($9 billion).

"One couple brought us 10,000 marks, the money they had received as a wedding present. They had wanted to pay for their honeymoon with it, but they misplaced the money and the trip had to be cancelled. After 11 years, they found it while moving and were able to go on a honeymoon after all."

Thus the marks make their way back to their origin, the Bundesbank, where they're now exchanged into euros free of charge and for an unlimited time. On average, 2,000 people exchange 560 marks at the bank's branches every day, Deichert said. But Germans aren't the only ones who've stashed deutsche marks.

"There's surely quite a bit abroad," said Deichert. "In the days of the D-mark there was an estimate that around a quarter of the D-mark supply was in circulation abroad. But we don't know how much."

A sizable stock of marks is likely to be found in eastern Europe, particularly in the countries that used it as a parallel or even as an official currency, such as in the Balkans.

Lost to wishes in foundations

The Bundesbank expected that a lot of the marks wouldn't come back to them, at least when it came to coins, Deichert said.

"There were estimates that around 40 percent of the coins wouldn't come back," he explained. "That's on the basis of other monetary reforms, such as in Britain. The coins may have disappeared into fountains, become part of collections. We always assumed the majority of notes would come back. We certainly didn't expect that it would take place over such a long amount of time."

Germans still have opportunities to spend their marks too. NGOs, like the Red Cross, and schools collect them for charitable causes. Stores put on events in which customers can pay with whatever marks they still have. But the supply is continually shrinking, for when they're turned in to the Bundesbank, their days are numbered.

"The notes are immediately shredded," Deichert said. The coins are first deformed and later melted down, and the raw materials are then used for other metallic bonds."

The silver coins, say, can be used in glasses frames and sparkplugs as well as for one and two euro coins. Perhaps that gives the mark's fans some consolation: Though they have euros in their wallets, they may just be paying with a bit of deutsche mark, too.