| During formation of coal, organic material from plants and trees becomes coalified by the effects of heat, pressure and geologic time. |
| Macerals are coalified plant remains preserved in coal and other rocks. |
| Plant megafossils preserved as coalified impressions are fragmentary. |
| Peat deposits can be coalified by heat and pressure over time following stratigraphic burial. |
| Ultrastructurally, parenchymatous cell walls are coalified, whereas microcrystalline pyrite plus coalified material were observed within lignified cell walls. |
