Beats Me
To construct such a huge complex image would take ages and unimaginable skill.
https://www.msn.com/en-gb/money/technology/brits-left-baffled-by-strange-ufo-type-marks-that-have-appeared-on-welsh-beach/ar-AA1iOCH2?ocid=msedgntp&cvid=21e8bf28568746ddb29b18d3a39e30db&ei=32#image=2