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Trains, now on Uber. T's and C's apply. Check the Uber app. This is scientific Americans 60 second science.

I'm Adam Levy.

Open up a clam and you might see the making of a tasty snack.

You probably wouldn't expect to find the history of our planet.

But that's what researchers have been deducing from a 70 million year old fossil clam.

They opened up this mollusk's secrets

by drilling a small hole in its shell with a laser

and analyzing the pattern of growth.

So we make a cross section through the shell. When you see the layers, the grove layers. of growth layers to

layers to shell did like the layers of the tree and that's allowed us to

really count the number of days in the near that far back inside.

Neel's to Winter pale paleoclimatologist at the Free University of Brussels in Belgium.

Using a laser to carefully count the number of growth rings in a 70 million year old fossil might seem like quite a laborious way to find out the number of days in a year.

After all, we all know the answers 365 and 366 in leap years, right?

That's interesting because what we found is actually that there were nuts

365 years ago.

There were a few more.

You see, Earth's spin on its axis gradually slows down over time. The reduction is due to the friction from Earth's tides which are driven by the Moon's orbit.

Back to that ancient clam. By measuring the rings on this mollusk's shell, the team was able to put a precise

number on the history of this process. 70 million years ago, the faster rotation of the earth

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