Plain, sharp-edged holes in seashore sand

Plain, sharp-edged holes in seashore sand

Observation - Plain, sharp-edged holes in seashore sand - UK and Ireland. Description: A profusion of sharp-edged holes of a variety of sizes - a common feature of wet/damp sand above the current strandline. Made by creatures? How? (Where is the 'spoil'?) What creatures? Or some physical process at work? - possibly related to gas movem

A profusion of sharp-edged holes of a variety of sizes - a common feature of wet/damp sand above the current strandline. Made by creatures? How? (Where is the 'spoil'?) What creatures?
Or some physical process at work? - possibly related to gas movements arising from tidal inflow? - or methane generation from buried rotting seaweed? (But again, where is the 'spoil'?)