Blasts from the past

The constantly shifting sands have recently exposed an old World War 2 sea mine that had been floating about the North Sea for the last 70 years before becoming beached. The mine is quite safe now with the casing being full of holes while the horns that acted as contact detonators have long since broken off.
The pieces of broken reinforced concrete are from a gun emplacement that was blown up when it became redundant at the end of the war