How are fossils formed? STEPHEN CHAN King George V School Fossils are the remains or traces of an animal or plant from an earlier age, usually in the form of bones which have been converted into rock or impressions. There are also several places where the footprints of extinct animals have been fossilised. While this process takes thousands of years, the vast majority of organisms do not turn into fossils. There has to be the right combination of factors to ensure a plant or animal ends up as a fossil rather than just rotting away. Usually only organisms with a solid skeleton or shell end up as fossils. Insects preserved in amber, the preservation of mammoths in Arctic ice and of woolly rhinoceroses in oil-saturated soil in Poland are rare examples of the preservation of soft tissues. Soon after death the animal or plant has to become buried in sediment or some similar material which protects it from weathering and excludes oxygen and bacteria, thus retarding decay. The sediment at the bottom of the sea and natural deposits of asphalt provide ideal conditions for fossils to form. Under the right conditions, the hard parts of the animal are eventually replaced by minerals leached through the, usually, sedimentary rock laid down around it. Sometimes the shell or bones are dissolved, leaving only an impression in the rock, which can be used to make a cast of the long-dead animal. Occasionally this mould is filled by minerals and forms a natural cast of the animal. Why is Styrofoam dangerous to our environment? Styrofoam is a trade name for a product called polystyrene. The problem is that it will not decay in landfills. Some polystyrene contains CFCs, chemicals that damage the ozone layer. The CFCs have been replaced by another chemical combination called HCFC-22. While this is better, it is still not great, because HCFC-22 can cause air pollution. Why do we sneeze? There are many super-sensitive nerve cells on the mucous mem brane which lines our nose. When the nerve cells detect a foreign substance, such as dust, or a strong smell, they will send a message to the brain. The brain will tell us to draw a deep breath. Our chest muscles will contract, and we will sneeze. Cold air also stimulates the nerve cells on the mucous membrane.