We’ve all heard about the cycle of life before, but have you ever wondered what happens to Earth’s creatures after they’re gone? I’m not talking about their spiritual journey (the theories and multiple beliefs on that alone could generate a year worth of blogs) but rather, what happens to their bodies? How are fossils created?

The simple answer is our planet re-absorbs them. In most cases, they even get turned into something else as time passes. Something we can often use in the modern world.

How Fossils Are Turned Into Chalk

Yes, you read that correctly. We use the converted remains of once-living organisms in day to day life. In fact, there are many products we use that were derived out of once-living beings, in one form or another. One of the biggest examples of this is fossil fuel (petroleum, coal, and natural gas), but a more fascinating example—at least for me—is chalk. Remarkably, those little white sticks your teacher used to write math and grammar lessons on the blackboard were formed out of compressed skeleton debris from the large numbers of plants that floated in the tropical sea 130-65 million years ago, during the Cretaceous period.

If you could look at the composition of chalk under a magnification of about a thousand, you can see the dried out skeletal carcasses known as coccoliths. They were made out of calcium carbonate (giving the fossil rock its signature white color), which used to be extracted out of the sea water by the then-living plants. When they died, the skeletons fell to the sea bed and was compacted over millions of years to form the chalk rock we see and use today .

Most known as coming from the White Cliffs of Dover, in England, chalk can also be found on the Islands of Mon (Denmark) and Rugen (Germany), as well as along cliffs in Northern Ireland and France. Despite the rarity of the locations it can be found, chalk is still used for a variety of purposes, not the least for writing on blackboards. It was once used to draw those white lines that separated court boundaries in racket sports, such as badminton or tennis. You can find tailors using chalk to outline their designs on fabrics, and its being used in agriculture to treat soils that are too acidic. Mountain climbers or gymnasts still use it to remove perspiration from their hands, and even your toothpaste can have a small amount of chalk in it….

Yes, I know you are stuck on the fact that you brush your teeth with toothpaste that potentially contains the fossilized remains of a prehistoric creature—a very many fossilized creatures—but I will leave you with something else that is food for thought. The name “Cretaceous” is partly derived from the Latin “creta” for chalk, meaning that one of the most significant features of the Cretaceous era was the formation of chalk. What will be the fossil deposits that will define our era? How will the remains of humans be used in millions of years, by the newest inhabitants of Earth?

I’m sure just the thought of that makes you shudder to think about it, yet who ever hesitates to use a piece of chalk? It’s the perfect example of the cycle of life, no matter what belief system you adhere to. Perspective will no doubt be different again in another million or so years.

If you liked this blog post, check out one of our other science articles.