Ordovician Toadstool Stromatolite from Wisconsin

Somehow this Paleozoic stromatolite has escaped the metamorphic processes of the earth, and essentially retained its "living" form. Coming from the Lower Ordovician Oneota Formation, it is some 495 million years old, it is from a time that Prokaryotic life forms no longer had exclusive use of earth's shorelines. By this time in geological history, microbial communities consisted of complex consortia of both prokaryotic and eukaryotic forms with diverse metabolic needs, and competition for resources and differing motility among them made for an intriguing microcosm of interacting life, some autotrophic, some chemotrophic and some heterotrophic.

Remaining in its ostensibly natural form, this stromatolite would be great either for display or as a teaching tool. Apparently, it comes from a tidal environment that eroding the stromatolite rendering the toadstool-like appearance.