Placed by the waves or by humans?  Doesn’t matter to me — it’s elegant and eloquent either way.  It feels like a piece of dance, and the repetition of the form in the lower right-hand loop is extraordinary.  Love the several triangles.  And the shadows in the sand and the reflections in the water surface. I didn’t notice most of those things when I took the photo, just thought it was a graceful form.  Noticing to take the picture is good; noticing more afterwards is a continuing gift!