Ammonoids

extinct cephalopods · ancient seas · fossils · spiral shells

Spiral shell hunters. Ammonoids had beautiful coiled shells that looked like spirals, and they were carnivores that hunted smaller creatures in ancient oceans. Today we find their fossils as hard, stone shells that tell us about life millions of years ago.

Super long history. These amazing animals first appeared about 410 million years ago and lived through the age of dinosaurs for over 340 million years. They finally disappeared around 66 million years ago when a giant asteroid hit Earth, just like what happened to the dinosaurs.

Octopus cousins. Even though ammonoids looked like nautiluses with their coiled shells, they were actually more closely related to modern octopuses, squid, and cuttlefish. They all belong to the same family of smart, ocean-hunting animals called cephalopods.

Ocean dominators. For hundreds of millions of years, ammonoids were among the most successful animals in Earth's oceans, living in seas all over the world. They came in many sizes and shell patterns, from tiny ones to giants bigger than a person.

Valuable treasures. Because ammonoids died out so long ago and are found as beautiful fossils, people have collected and studied them for centuries. Their shells are prized by fossil hunters and museums around the world.