This is a compilation of my favorites from the wonderful computer animation/simulations of the fantastical extinct precambrian sea creatures by the Royal Ontario Museum at this website about the Burgess Shale:
burgess-shale.rom.on.ca/en/fos...
You can click on any of the animals shown and look for the 3D animation they created for that animal. I just picked a bunch of my favorites and strung them all together into a video clip that simulates what it would've been like to scuba dive in a precambrian ocean, seeing all the animals that are now extinct.
The Burgess Shale is a unique fossil record that shows in extremely fine detail the remains of truly fantastical animals that all went extinct at the same time. These aren't just older versions of the animals that live on Earth now -- this was a whole different direction that life was taking and had they survived life on Earth would look very, very different than it does today. We're talking animals that are not bilaterally symmetrical, have odd appendages like trunks and snouts and swim-jets that no animal today has, and just totally different body plans that did not survive.