Top of the encrusted surface of a brachiopod shell, showing the “war” between an edrioasteroid (star-shaped organism at center) and a fast-growing bryozoan colony. From Sprinkle and Rodgers 2010.

Back in the early days of paleontology, when the meaning and origin of fossils was still in doubt, some naturalists believed that the shells, shark teeth, and other petrified curiosities were attempts by the rock to imitate life. Fossils were not true vestiges of history, it was believed, but instead the product of some “plastic virtue” suffused throughout the non-living Creation. As naturalists began to study fossils more closely, however, they realized that the ancient shells showed signs of growth just like their counterparts along the seashore.