Worm cast and breathing hole mmade by a marine worm
No interactions present.
MarLIN states the Black Lug rarely forms a blow hole as here so more than likely to be Arenicola marina.
That was my original identification. Black lug are not found at this location although common in the mud of The Wade and Hamford Water nearby.
I know sorry, I was just showing off a new bit of knowledge I had read on the MarLIN website a few minutes beforehand!
Lat/Lng: 51.854806, 1.28106
OS grid ref: TM260224
Flat sandy beach