After a little bit of help here, I was taking a walk along Omaha beach (france) last week after a little storm and saw something sticking out of a sand dune, I had about 30 minutes of digging before having to leave for a ferry and managed to uncover as much as I could, the item seemed to be threaded into wood?? the flip flop is a size ten (about 1 foot long) to give an idea of size.
Can anyone ID what this was? it's still stuck in the dune on Omaha!!
Thanks to all replies, I am sure I have seen this shape before but can't place it.