Gessner’s ‘Book of Fossils’ is the last of eight treatises by various authors in the anthology he edited, ‘On Every Kind of Fossil’. In it, he relates stones to various aspects of nature and to artefacts on the basis of similarities in appearance or the meaning of their names. Chapter 14, on stones that resemble aquatic creatures, includes illustrations of fossilised sea urchins and shark teeth, as well as a fossilised crab that is now held at the NMB.