Bordered holes in seashore sand.

Bordered holes in seashore sand.

Observation - Bordered holes in seashore sand.. Description: Relatively modest numbers of neatly edged holes appear in sand above the current strandline, apparently produced by / the homes of / small creatures of uniform size. What creatures?

Relatively modest numbers of neatly edged holes appear in sand above the current strandline, apparently produced by / the homes of / small creatures of uniform size. What creatures?