Carbonaceous film (paleontology)

It is a type of fossil found in any rock when organic material is compressed, leaving only a carbon residue or film.

When an organism is buried under many layers of sediment, pressure and heat increase during diagenesis and if the organism lacks a hard skeleton, it will only leave this thin film of carbon residue on rock surfaces.

As sediment piles up, the organism's remains are subjected to pressure and heat.

[1] Plant fossils often occur as a residue or film of carbon.

[2] The delicate fossils of the Burgess Shale include carbon film forms.