[dread78645]

Something is not right here. The article says the organisms were 560 million years old - or basically late Precambrian. But the Burgess is Middle Cambrian (505 million years old).

Most articles mention 530 mya.

The Burgess shale is the accumulated silt from a reef that runs some 13 miles under four mountains.
I don't think anyone could factually say that the entire layer is 530 (or 505) million years old.

[dirtboy]

I don't think anyone could factually say that the entire layer is 530 (or 505) million years old.

Age is less important than era here. If these fossils were found in the Burgess, they cannot be Pre-Cambrian, since the Burgess has been placed in the Middle Cambrian - but the date given (560 million years old) IS Pre-Cambrian.

So something is wrong here.