Cockles and mussels, alive, alive oh ...
Bivalves are another group of mollusc that you can recognise today. Cockles, mussels, and oysters are all bivalves.
They live inside shells with two parts, known as valves, that are usually mirror images of each other. These valves open so the animal can feed, and close to give the animal protection.
All bivalves live in water, and most of them are found in the sea. They feed by filtering out small food particles from the water around them. Most live buried in sand or sediment. Some can attach themselves to hard surfaces or bore into rock. A few can even swim.
Fossil scallop shells and Gryphea, which is sometimes called the devil's toenails!
The oldest bivalve fossils are over 500 million years old. Because bivalves are still common today we know a lot about how they used to live. The shape of their shells can tell palaeontologists if they swam or if they burrowed, and the type of environment they lived in. Huge numbers of fossil bivalve shells can form limestones.
You can find fossil bivalves that look very like modern bivalves.
The molluscs are split into different groups - the gastropods, bivalves and cephalopods. The cephalopods are also split into three groups.
If you read these pages you should become an expert invertebrate identifier!
The major groups are listed below - select a link to learn more about this type of fossil.
Echinoderms Return to the wheel
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