fossils

• fossils are the remains of organisms from many thousands of years ago, which are found in rocks. they provide evidence that organisms lived a long time ago
• fossils form in rocks in one of three ways: from gradual replacement by minerals ; from casts and impressions ; from preservation in places where no decay happens
• peat bogs are common places for fossils as they are too acidic for microbes
• fossils are sometimes formed when an organism is buried in a soft material like clay
• bones, teeth or shells do not decay easily, but are eventually replaced by minerals as they decay