The tree of life on Earth is big and messy, suggesting it
would not be improbable to find life on other planets.
The strangeness of the animals discovered in the Burgess
Shale strained the efforts of many including Wolcott to force them
into existing phyla. Today, scientists are more likely to create
new phyla to accommodate these creatures. Many of these animals
are arthropods, that is, invertebrates with exoskeletons.
See also in The book of science:
Readings on wikipedia:
Museum sites also describe numerous species found in Burgess