The first skeletons
Animals begin building shells from minerals — and something immediately starts drilling holes in them.
- When
- Known to
- ± 5 million years
- Era
- Neoproterozoic, Proterozoic
Cloudina, a tube built of stacked calcium carbonate cones, appears around 550 million years ago and spreads worldwide. It is among the first animals to biomineralise, and some specimens carry neat circular borings — the earliest direct evidence of predation on a shelled animal. Armour and the means to defeat it arrive together, foreshadowing the arms race that defines the Cambrian.