The piece first emerged about three hundred meters from the shore in the summer but it was only a couple of weeks ago that workmen were able to dig around it to free it from the sand.
What has emerged is an intriguing mystery and it could date back to the Second World War when Granville was used by the Germans to take supplies to the channel island of Jersey which was occupied by German forces.
It is one piece of metal measuring eight meters by three meters which appears to have been folded over. There is speculation that it could have been part of a German vehicle being move to Jersey which is 33 off the shore at Granville.
The Germans used boats to get supplies to Jersey after they occupied the island in 1940 until 1945. They were then used during the war to keep a supply line open between the island and Normandy.
After D-Day as the Allies moved south German supplies were often blown up and destroyed so that the advancing armies could not use them. One possibility is that this chunk of metal is part of a boat that was destroyed at that time in 1944.
Local historian Phillippe Letouzey believes that the rivets are very similar to those that were used on the Rhine barges. â€˜It is not welded but riveted so that suggest it was made in the 1940s. It might be a bit of a barge on the Rhine,â€™ he said. But the structure has windows that were not used on these vessels and it is unlikely to be a fishing boat.
The Tourist Office in Granville is asking for ideas and information from the public to try to find out what it could be. They hope someone who lived in Granville in the 1940s or from Jersey might remember a boat being used at the beaches and left there after the end of the war.
Anyone with information is being asked to contact the tourism office on 02 33 91 30 03 or send an email to firstname.lastname@example.org