Sorry didn't realise the photo was that bad what it shows is three individual holes grouped together they are spaced over a wide area sometimes singly sometimes in groups and are shallow depressions of between 6" to12" in size roughly oval in shape.
Roller, it looks like somebody has been digging lug, & because the tides are small they have'nt filled back in properly!
I would be tempted to say they were "flattie flaps" if they were down on the low water mark, where the flatties flap the sand to (a) hide themselves from predators, or (b) try to dislodge bivalves hidden just under the surface, nobody really knows which it is, but they do make depressions for some reason or another, but they are shallow, these look too deep for that, I reckon a lug digger for this one!
He must have been a bloody (can I say that Mike?) industrious digger - there were hundreds of them I was afraid someone was going to say flatties because I fished right over them-as the tide came in and didn't have a bite
the mystery of corn circles has now hit the beach are aliens behind this?. Sorry for that on a serious note i believe they have been done by flatties/rays. How far out of they? Have seen something similar like that on my local beach.
i presume the beach is cefn sidan or very close to it, mate, what bait did you use? its no good fishing crab or fish baits over these marks as they are definetley flounder feeding marks they were probably near to some tube worm marks on the beach, if you scratch through these marks you will quite often see broken bits of small white rag which tend to congragate around the tube worms but dont forget that those marks were made on the last tide and fish swim?