Corals
Corals are made up of small invertebrate animals, known as zooids, that look like tiny sea anemones. They feed on small food particles they find in the water around them.
Together, many zooids form colonies, many colonies form reefs. Coral reefs can be massive structures, stretching hundreds of miles. The Great Barrier Reef in northern Australia can be seen from space.
The oldest coral fossils are over 500 million years old. The earliest forms were different from those we see today and they died out 225 million years ago. Modern corals are still common in tropical oceans.
These are solitary corals from the Jurassic and Cretaceous periods.
Corals are very important fossils. Many corals have a hard exoskeleton made of calcium carbonate.
It is this exoskeleton that is usually fossilised. When the coral dies, the skeleton can be broken down to form limestone, an important building stone.
These slabs of marble were polished to show fossilised corals within the stone.
Fossil corals also tell us about the past. Since many corals live in warm, shallow sea water, their fossils are good indicators of environmental conditions.
Fossil corals found in England tell us that it must have had a much warmer, tropical environment at certain periods in its history.
