This is a picture of a Hallucigenia
When the bizarre animal was first discovered in the Burgess shale of the Canadian Rocky Mountains, scientists couldn't tell its head from its tail.
The Cambrian explosion was when life ¨exploded¨
541 million years ago in the Cambrian period, during which most major animal phyla appeared.
That is when the Cambrian explosion happened
The Cambrian explosion or Cambrian radiation was the relatively short evolutionary event