Stone Borers

marine animals and plants that destroy rocks, coral, and mollusk shells. Stone borers include some species of marine algae, sponges, bristle worms, barnacles and iso-pod crustaceans, bivalves and gastropods, and sea urchins. Most stone borers make passages in rock mechanically (crustaceans, bivalves of the genus Pholas, sea urchins), but some destroy rock by chemical means, secreting an acid substance (blue-green algae, worms, and, of the bivalves, the “sea dates” of the genus Lithophagus). Stone borers use the passageways they have made as hiding places from enemies, as a place in which to keep wet during ebb tides, and as a refuge from breakers. Rocks that have been largely damaged by stone borers are eventually completely destroyed by the action of waves. In subtropical and tropical seas stone borers do much damage to concrete structures.