They were cephalopods with spiral shaped shells, and they range from around two centimeters to more than two meters across.

Today they're extinct, but you confined their fossilized shells all over the world.

I am a knight.

Fossils make for some pretty rocks, but there's one place in the world where they have turned into rainbow colored gems.

It's southern Alberta in Canada, and we're not entirely sure why.

When they were alive, ammonites shells were made of a mineral called a rag a night.

It's a compound made of carbon, calcium and oxygen, and in the center of that show, it combines with organic material to form something called Maker.

You might know it better.

His mother of pearl and ammonites Nature layer is pretty to begin with, but in certain fossils it becomes way more vibrant in color.

When that happens, we call it am a light.

It's amazing to look at, but it almost shouldn't exist because a rag a night isn't stable over really long time spans.

At least at the pressures were AMA night fossils, air hiding out.

The Adams normally rearranged themselves into a more stable structure and form the mineral calcite, which is much less fun to look at.

But in southern Alberta, something stop that from happening.

The challenge now is to figure out what it wasa do that scientists are looking at.

The Bear pa formation the layer of rock were analysed has found more than 70 million years ago.

This area was covered by a vast seaway, but ultimately volcanic activity filled it with ash that killed all the marine life, including several species of ammonites and further geologic activity buried them properly.

Scientists don't think this is a normal burial, though.

They're evidence suggests the ammonites got buried really fast and we're exposed to heavy pressures that could have compressed the Iraq and I enough to keep it from rearranging itself into calcite.

Additionally, the Bear Pond region had high concentrations of iron and magnesium, and although it isn't quite clear how that may have helped protect the Iraqi night further, maybe the iron based minerals formed a sort of shield around the fossils.

In any case, not all of the ammonites found in the bear paw formation went on to become gem quality am ally, so Whatever the processes were at work, they didn't affect every shell the same way.

Still, the stuff we do have is really gorgeous because of how light acts within it am, Allied can look like a rainbow.

When white light enters thin plates of raga night crystal, it gets split into its constituent colors to a process called diffraction.

The exact color depends on how the crystals are arranged and what impurities exist within the lattice.

But you can get some really cool combination.

Emily.

It can even look different colors from different angles, depending on how you see the light pass through it.

Scientists will keep investigating how these fossils formed.

But one way or another, the story is amazing.

A funny looking sea creature from millions of years ago became a beautiful Jim Am.

Alight is a gift rarer than diamond, which honestly is not actually saying much because diamonds aren't that rare.