There are certain rock-boring animals, such as the pholas, which help to decay the rocks.
"Vanishing England"
P. H. Ditchfield
When these flints, probably long exposed in the atmosphere, became submerged, they were covered with barnacles, and the surface of the chalk became perforated by the pholas crispata, each fossil shell still remaining at the bottom of its cylindrical cavity, now filled up with loose sand from the incumbent crag.
"The Student's Elements of Geology"
Sir Charles Lyell
This species of pholas still exists, and drills the rocks between high and low water on the British coast.
"The Student's Elements of Geology"
Sir Charles Lyell
