|
Fossils are
preserved signs of
life, usually dug up from rocks (hence the name from the Latin fossilis). Sometimes fossils are actual remains of life, such as bones. Other times fossils are stones and minerals that have replaced the remains in such a way that the minerals hold the shape of the original remains. Often, fossils are a mix of original remains and mineralized remains. There are also fossils that are made as impressions, molds, or casts in rock. Tracks, for example, can become fossils. The oldest fossils are microfossils (fossils of cyanobacteria) from about 3,456 million years ago (3.456 billion years ago).
|
|
