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What are fossils and how are they formed?

Fossils are preserved remains or traces of animals, plants, and other organisms from the remote past.

Fossils are formed through a process called fossilisation. This process begins when an organism or evidence of its activity (like footprints) is covered by sediment, such as sand or mud. Over time, more layers of sediment build up and exert pressure on the layers beneath, causing them to harden and turn into rock. This process is known as lithification.

The organism's remains can be preserved in several ways. If the organism had hard parts, like bones or shells, these can be preserved as they are, often with the organic material replaced by minerals over time. This is known as permineralisation. In some cases, the hard parts can dissolve, leaving a mould that can be filled with sediment or mineral deposits to create a cast of the original organism.

Soft parts of organisms are rarely preserved, as they usually decompose before fossilisation can occur. However, in some special conditions, such as rapid burial or lack of oxygen, soft parts can be preserved as well. They can leave impressions in the surrounding sediment, or be preserved in fine detail in amber or tar.

Fossils can also be formed through the preservation of traces of an organism's activity. These are known as trace fossils and can include footprints, burrows, or droppings. These fossils can provide valuable information about the behaviour and environment of the organism.

Fossils are incredibly important in helping scientists understand the history of life on Earth. They provide a record of past life and environments, and can help us understand how life has evolved over time.

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