Ammonites

Ammonites were sea creatures with beautiful spiral shells. They lived for hundreds of millions of years. They went extinct at the same time as the dinosaurs, 66 million years ago. Ammonites are related to modern octopuses, squid, and nautiluses.

Spiral Shells

Ammonites had coiled shells divided into many chambers. The animal lived in the outermost chamber. It could fill the other chambers with gas to float up or down in the water. Some ammonite shells were tiny, while others were over 5 feet across! That is wider than most people are tall.

Life in Ancient Seas

Ammonites had tentacles for catching food, like their squid relatives. They swam by squirting water out of their bodies. Ammonites are some of the most common fossils in the world. Scientists use them to figure out how old rocks are. Different ammonite species lived at different times.

Fun Facts

• The biggest ammonite shell ever found was over 5 feet across.
• Ammonite fossils are so common they are found on every continent, including Antarctica.
• In the Middle Ages, people thought ammonite fossils were coiled-up snakes turned to stone.

Did You Know?

Ammonite fossils are so useful that scientists use them like a clock. If you find a certain type of ammonite in a rock, you can tell roughly how old that rock is!