If geologists could choose a ‘canary in the coal mine’ for dramatic climate change, corals, and reefs in general, would be it.

This has been true throughout the past half a billion years of geological history, basically since animals evolved, during which time the world has experienced significant fluctuations in climate.

Over hundreds of millions of years many animals have built reefs, from sponges to corals to bryozoans to bivalves and back to corals. But just as today’s coral reefs are sickening from the impacts of human-induced climate change, the ancient ocean reefs of the Earth’s deep past suffered when their environment changed. This is because reef-forming animal groups are sessile, which means they grow fixed in one spot on the sea floor. So a catastrophic collapse of the base of the food chain or a change in environment that they can’t escape (such as loss of oxygen) will hit these reef builders the hardest.

The coral species pictured here lived four hundred million years ago. It belonged to the taxonomic order Rugosa. Rugose coral species were either solitary, like this one, or colonial.

The fossil specimen was found in Lilydale in Victoria. It is part of the Museums Victoria Invertebrate Palaeontology Collection.

Curation notes by: Dr Rolf Schmidt, Collection Manager Invertebrate Palaeontology, Museums Victoria, and Lucinda Horrocks, Wind & Sky Productions.