Colombellinidae was a family of small marine snails that inhabited warm shallow seas during the Jurassic and earliest Cretaceous.

Research conducted on Seymour Island has shown that stalked crinoids continuously inhabited the shallow seas of Antarctica from the Late Cretaceous through the Paleogene.

The echinoderm skeleton has a remarkable microstructure known as stereom. It is composed of calcitic trabeculae with curvatures close to “saddle-shaped” forms, characteristic of minimal surfaces…

Shells of marine gastropods from hydrothermal vent environments are coated with inorganic materials of unknown composition. Conversely, their fossil equivalents are known exclusively from outer moulds in pyrite (FeS2), with no shell material left.

Methane (CH4) is largely built from the light carbon isotope (12C). When emitted from the seabed, methane is oxidized by sediment-dwelling microorganisms, with one of the byproducts being methanogenic carbonate cements, themselves with large amounts of the 12C.

Ammonites, extinct cephalopods dominant in Mesozoic marine ecosystems, are often listed amongst victims of the end-Cretaceous mass extinction (66 Ma).