Imprints of the organism embedded in rocks.
These are formed when external molds are filled with sediment.
These occur when sediment fills the shell of a deceased organism, such as a bivalve or a gastropod. These remain after the organism's remains decompose to show the internal features of the organism
These occur when minerals slowly replace the various organic tissues with minerals.
These occur when over time all parts of the original organism except the carbon are removed from the fossil over time. The remaining carbon is the same carbon that the organism was made of.
These occur when original minerals in the fossil over time revert into more stable minerals, such as an apatite shell recrystallizing into the more thermodynamically stable calcite.
This occurs when the hard parts of the organism are replaced with minerals over time.
These fossils are fossils that aren't exactly part of the organism. These include footprints, burrows, eggshells, and my personal favorite, coprolite (or fossilized excrement).They give insight into an organism's behavior.
These are much rarer than other fossil types. These are still intact parts of the organism. Actual remains can be seen preserved in ice, tar, or amber. A good example is mammoth hair. It is often frozen and still preserved.
Free swimming, such as fish or scallops (scallops "swim" by flapping their shells. It's kinda cool).
Rooted to the floor. Examples include crinoids (sea lilies) and sea anemones
Lives on the sea floor, e.g crabs, lobsters, crinoids
Free swimming, same as pelagic.
The opposite of sessile; moves around. Examples include anything that is Pelagic/Vagrant, Benthic, or any other organism able to move around.