Learn about Ammonites

Aesthetic Ancient Creatures

Jurassic Ammonite. Illustration by Nobu Tamura.

Few fossils capture the imagination quite like ammonites. Across time and culture—from Aboriginal Australians to ancient Egyptians—these spirals have been revered as natural symbols of time, symmetry, and transformation. Their graceful curves follow the same logarithmic geometry found in hurricanes, galaxies, and nautilus shells: nature’s recurring signature.

Ammonites were marine cephalopods—ancestors of today’s squid and octopus—that thrived in prehistoric oceans for over 300 million years, from the Devonian to the end of the Cretaceous. They ranged from small, delicate shells to giants exceeding three meters across, living among the marine reptiles that patrolled those ancient seas.

To survive in turbulent waters—and to elude predators such as mosasaurs—ammonites controlled their buoyancy with remarkable precision. Through a narrow tube called the siphuncle, they adjusted the gases and fluids inside their internal chambers, allowing them to rise, sink, or glide effortlessly.

The Iridescent Ammonites of the Bearpaw Formation

Among the most spectacular ammonites ever discovered are those from the Bearpaw Formation of southern Alberta. These fossils, around 70 million years old, have undergone a rare process of mineralization that transformed their original aragonite shells into sheets of radiant colour—fiery reds, greens, and golds shimmering like opal.

This gem-like material, known as ammolite, is prized not only by collectors but also as a gemstone in its own right. Each specimen reveals a fusion of art and geology: the remnant of a once-living creature turned into a natural mosaic by millions of years of pressure and transformation.

These iridescent ammonites are more than fossils—they are the earth’s own expression of beauty across deep time.

Explore our ammonite collection to see select examples from the Bearpaw Formation and beyond.