Amazing preservation in fine grained mud of a shrimp-like animal that was alive 520 million years ago, What we have managed to find out about life during this period in Earth's history is from examples of exceptional preservation like the Burgess Shale in Canada, and this site in China.
It was around this time that life with hard parts first appeared and so the amount of fossilised material we find increases a great deal compared to earlier on in the record, although it's still not a lot.
There's still a lot of debate as to how any of the fossils we find from so long ago are related to modern life-forms, or indeed whether some of them are animals at all. It's very rare to find such fine detail of the soft body parts preserved, and even more rare to find something so similar to structures we see in modern day animals.
Scientists said on Monday they have found a fossil of a shrimp-like creature that lived 520 million years ago with an exquisitely preserved heart and blood vessels that represent the oldest-known cardiovascular system