Painted from a photo I took on a trip to the Washington coast several years ago. It was a cool rainy day, and the headlands and sea stacks were obscured by rain and mist. A very low tide exposed lots of large rocks along the seashore. A friend and I explored the tidepools and saw lots of rocks that looked like swiss cheese. Some sort of mollusc, or possibly a sea urchin, bored these holes into the solid rock for protection.