Agatized Gastropod Fossil

This fossil was the shell of a snail that lived around 54 million years ago.

The family of gastropods make up one of the most diverse collections of species on Earth, second only to insects. It is estimated that there are around 24,000 species of terrestrial gastropods, 35,000 aquatic species, and 15,000 extinct species. The species this shell belonged to is still unknown, but it has been dated to the Eocene period.

The soft bodies of these creatures typically decay too fast to fossilize, but the composition of the shell is ideal for preservation. This shell hasn’t just been fossilized, instead its cavities have been replaced primarily with microgranular quartz. This form of fossilization is called agatization.

Gastropods are among the longest surviving lineages; the earliest fossils date to the Cambrian Period about 500 million years ago and their descendants continue to thrive today.