The animals in this story come from the mid-Cambrian period, 505 million years ago, when our planet was a very alien world. These animals were preserved in the fossils of the Burgess Shale in British Columbia, Canada.

The Burgess fauna was considered so weird that it prompted a big debate. Are these species just dead-end experiments or the ancestors of modern life? You can read the arguments in books by Simon Conway-Morris (Crucible of Creation) and Steven J. Gould (Wonderful Life).

The animals have been popular in Japan, inspiring such things as toys and a dating simulation video game, and appearing in the anime Neon Genesis Evangelion. Canada's Royal Ontario Museum sells awesome Burgess toys.