Marianne Winkler found an old bottle on a beach on Amrum Island, Germany earlier this year with a postcard from the early 1900s inside. Instructions printed on the card asked for its discoverer to mail it back to the Marine Biological Association of the United Kingdom in the care of George Parker Bidder. The message promised a shilling in return.

“We haven’t had [a bottle] returned in living memory,” says Guy Baker, an MBA spokesperson. “So when this one turned up in April it was quite a surprise.”

Now the MBA believes postcard returned to them in April may be the oldest message in a bottle ever found.

The bottle was released into the North Sea between 1904 and 1906 as part of research carried out by George Parker Bidder, who was the MBA President from 1939-1945 and was remembered for his scientific research and also the large financial contributions he made to the Association.

Bidder released a total of 1020 bottles between 1904 and 1906 and he reported that his bottles were hauled up by the fishermen at the rate of 55 percent annually.

Click here to read an in-depth report by National Geographic on this specific incident and the long history of leaving messages in bottles to the ocean currents.