Not far from where I live in north Norfolk is a beach on which you can pick up smooth, pointed flints shaped like large bullets. These are not the remnants of some primeval battle, but fossils: the remains of squid that thronged here more than seventy million years ago during the age of the dinosaurs. When the squid died, their bodies fell to the sea bottom and were buried. All the soft parts – the tentacles, the eyes, the fins – rotted away. Only the hard remnant, known as the ‘pen’, was left. Slowly, the chalky material from which it was made was replaced, grain by grain, particle by particle, by silica, until it was entirely composed of flint.

Back in the day, before people had heard about evolution, and when the conception of time was constrained by the biblical story of creation, such a stone would have been seen as just that – a stone – or as the work of the Devil, intended to deceive. Indeed, the horny, warty shells of fossilised oysters are known as Devil’s toenails. When people grasped that these remarkable objects were the vestiges of animals rather than satanic detritus, they thought them, perhaps, to have been the corpses of creatures that perished in Noah’s flood, petrified as a testament to the event or as a warning. The skeleton of a supposed observer of the flood was even named Homo diluvii testis (‘human witness to the deluge’), until it embarrassingly became apparent that the bones were not human but came from a very large species of salamander.

We generally think of fossils, then, as stony impressions of the hard parts of ancient creatures – the bones, the shells, the armour. Very rarely, though, more than just bones and shells are left. Now and then, traces of soft tissue remain. Dale Greenwalt’s book is a waterfront