Clearly a bilaterally symmetrical cylindrical shape like this could not form by random processes. They certainly seem too regular to be a natural feature. The arrow points to some sort of structure. This specimen looks like an oak leaf that has been encrusted with minerals to form a fossil. Several views show the way it had curled up before being mineralized.
Arrows point to veins.
This pair of specimens was found exposed in an outcrop along a river. Photo by Chris Collom. Leisegang rings leisegang rings Leisegang rings are concentric bands of alternating coloration, typically found in sandstones, and typically with an orange, red, or brown colour. The water and oxidation processes diffuse inward along a discrete front, whose position varies depending upon the water and oxygen supply. In outcrop, concentric leisegang rings occurred around every fracture in the sandstone cliff this specimen was obtained from.