The first shells
And immediately: holes drilled through them
See it on the timeline →In depth
Cloudina and Namacalathus from the Nama Group are among the oldest biomineralised skeletons, around 550 million years. The shells are built of stacked calcareous cones, and a substantial fraction carry circular borings whose size distribution varies between localities — the pattern expected of selective predation rather than random damage. Biomineralisation is expensive, and arises repeatedly and independently through history, almost always in response to predators. The rise of shells is also why the fossil record becomes so much richer from the Cambrian onward: hard tissue preserves, soft tissue does not.
For children
In Namibia lie fossils of small tube-shaped animals that built shells of calcium carbonate — the first animals to make anything hard. And many of the shells have drill holes. The armour and the weapon appear at the same moment. The arms race still running in the ocean starts here.
Connects to
Part of Terra Saga — the story of Earth on a timeline. terrasaga.org