Geoworlds (for the unitiated, that's a SLURL, not a URL) is a project on the teen grid, run by the University of Kentucky, under an NSF grant to help teen students better understand epochs of geologic history. We have created model ecosystems for a variety of geologic time periods. Simulations of the Cambrian (from the burgess shale), Permian, Cretaceous eras have all been completed or mostly completed. I've installed Ecosystem Working Group style ecosystems in the Cambrian and Permian eras. I'm attaching an image from the Permian build, thus far my favorite. It's a nautiloid, a relative of today's nautilus.

We're trying to start logging the ecosystem experiment again. Apologies for the long delay.