The word ‘fossil’ comes from the Latin word fossus, which means ‘dug up’. Generally, the remains were once the hard parts of an organism, such as bones and shell although, under exceptional circumstances, soft tissues have also fossilised.
Impression fossils: fossils can also form when the remains decay completely but leave an impression in the sediment. Impressions can be of the external shape or internal space (which may fill with other minerals or sediment).
Mineralised fossil: these fossils are formed when organic matter in remains is gradually replaced with minerals, ultimately turning the remains to ‘rock’.
The following fossil images have been taken of my own collection or museum specimens.