Flint nodules are positive casts of negative spaces, once filled with organic life. They are trace fossils. During the Cambrian period of Earth’s geological history (541- 485.4 million years ago) sponges bloomed across the planet’s oceans. Crustaceans and molluscs bored into the seabed, creating burrows in the sediment. During their long life span (500–1,000 years) the sponges’ siliceous structures grew denser into overlapping layers of elaborate geometric forms known as spicules. As these organisms eventually perished, they dissolved into a gelatinous material, filling cavities and eventually hardening into silica. This explains the complex shapes of flint nodules that are found.

Certain types of flint, such as that from the south coast of England, contain trapped fossilised marine flora. Pieces of coral and vegetation have been found preserved inside the flint similar to insects and plant parts within amber. Thin slices of the stone often reveal this effect. Thinking laterally, the parallel derivation with the word plinth is interesting in this context, if we allow a reading of flint as a heavy stone base that holds up something to be examined.

The Swedish etymology of flint is a clipping of flintskalle, meaning ‘a bald head’.

Vilken flint han har fått!
My God, he has gone bald!

This is the reason my flint photographs are asteroids, not comets. The word comet is from late Old English, from Latin cometa, from Greek komētēs ‘long-haired (star)’, from komē ‘hair’.