To prevent destruction, the surface can be coated with a sealant. Coal balls can also be stored in an low-oxygen medium like glycerin or antifreeze. Permineralization with phosphate is uncommon for land plants, but can be important in some types of marine settings. Internal structure, especially of thick-walled, hard fruits is sometimes well preserved. These fossils may be sectioned by microtome or embedded and treated much like living tissues.
Compactions are most common in the youngest plant fossils.
Examine specimens of Tertiary fruits and seeds, and thin sections made from them. However, the pollen and spore shells, once spherical, are flattened by the compressive forces of lithification. As more becomes known about the chemistry of modern plants, paleobotanists have begun to examine the fossil record for corresponding chemical data. For example, characteristic breakdown products of chlorophylls and lignins have been found in well-preserved fossil leaves. Lipids and their derivatives have also been recovered from sediments.