Editing Pseudofossil (section)

==Background==
[[Pyrite]] disks or spindles are sometimes mistaken for fossils of [[sand dollar]]s or other forms (see [[marcasite]]). Cracks, bumps, [[gas]] bubbles, and such can be difficult to distinguish from true fossils. Specimens that cannot be attributed with certainty to either fossils or pseudofossils are treated as [[dubiofossil]]s. Debates on whether specific forms are pseudo or true fossils can be lengthy and difficult. For example, ''[[Eozoön]]'' is a complex laminated form of interlayered [[calcite]] and [[Serpentine group|serpentine]] originally found in [[Precambrian]] metamorphosed [[limestone]]s (marbles). It was at first thought to be the remains of a giant fossil protozoan (Dawson, 1865), then by far the oldest fossil known. Similar structures were subsequently found in metamorphosed [[limestone block]]s ejected during an eruption of [[Mount Vesuvius]]. It was clear that high-temperature physical and chemical processes were responsible for the formation of ''Eozoön'' in the carbonate rock (O'Brien, 1970). The debate over the interpretation of ''Eozoon'' was a significant episode in the history of paleontology (Adelman, 2007).

[[Chemical gardens]] can produce branching microtubuli of 2-10 μm in diameter and can resemble very closely the shapes of [[fossilized]] primitive [[fungi]] or [[microorganisms]]. It has been proposed that ancient, [[Precambrian]], structures that have been identified as the evidence for the first fungi or even the first life, are more probably products of ancient natural chemical gardens.<ref>{{Cite journal |last=McMahon |first=Sean |year=2020 |title=Earth's earliest and deepest purported fossils may be iron-mineralized chemical gardens |journal=Proc. R. Soc. B |volume=286 |issue=1916 |doi=10.1098/rspb.2019.2410 |doi-access=free|pmid=31771469 |pmc=6939263 }}</ref>

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Image:Dendrites01.jpg|Manganese [[dendrite (crystal)]] on a limestone bedding plane from [[Solnhofen]], Germany. Scale in mm.
Image:Concretion01.jpg|[[Concretion]] with calcite-filled septarian cracks. Scale in mm.
Image:Eozoon01.jpg|''Eozoön canadense'' from the [[Precambrian]] of Canada, a metamorphic rock made of interlayered calcite and serpentine. A well-known pseudofossil (Adelman, 2007). Scale in mm.
Image:ShatterCones.jpg|Cone-in-cone structures produced by compression of limestone. Sometimes mistaken for fossils, thus becoming examples of pseudofossils.
Image:Markasit hg.jpg|A [[marcasite]] crystal form resembling a sand dollar.
Image:Pseudocoprolite.jpg|A [[Miocene]] pseudocoprolite from Washington state. This is one of the most common pseudofossils because it so closely resembles a [[coprolite]]. Scale in mm. See Spencer (1993).
Image:ConcretionPseudofossil.jpg|Cross-section of a concretion showing layers that resemble tree rings.
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