That's really interesting... I gather that area fills up with water and drains back out again through the sand underneath? Is that like concrete or something surrounding it, yes? I'm surprised it has lasted and worn so well.
Congratulations on the win also! : )
That was the concrete basement for the German heavy artillery point during WWII, defending the gates to port. So Nazi did all very properly...and seems lasting forever
Exceptionally well being that close to the ocean and on the sand!