1 an organism dies. Anaerobic conditions exclude bacteria and other predators that consume bodies before burial, so organisms that die in the deepest ocean or in a deep lake are more likely to become fossils

2 the remains need to be buried in soft sediment. Rapid burial increases the chances of fossilisation because a body is less likely to be consumed or destroyed by the environment such as wind, waves and scavengers.

3 a period of burial, which can range from a few thousand years up to millions of years. During this time, the rocks around the body will change the shape, and the chemical and mineral composition, of the buried body parts.

4the rocks around the fossil need to be eroded, allowing them to become exposed to the Earth's surface in time for a palaeontologist to come past and find it.

when the dead organism decays and leaves a thin black deposit of carbon e.g. plant fossil

when a part of the organisms is chemically changed into another mineral

preserved remains of the imprint of the body ( footprints and track)