In this case, the xenacanthid shark is not much more but a time marker, indicating a late Palaeozoic age of the scene, if you are familiar for ancient fishes and faunas. A characteristic double-tipped tooth was indeed found in the redbeds of the Kyffhäuser mountains in Germany. But the story is about latest Carboniferous wood and its mineralisation. Not only are petrified trunks a great archive for environments, as well as their taphonomy preserves the sedimentary bedding conditions around. The very minerals that copied the original plant in sub-cell details helped scientists to reconstruct tectonic events throughout their silent history as a fossil – which is more than 300 million years!