amber

Our Living Language  : Certain trees, especially conifers, produce a sticky substance called resin to protect themselves against insects. Normally, it decays in oxygen through the action of bacteria. However, if the resin happens to fall into wet mud or sand containing little oxygen, it can harden and eventually fossilize, becoming the yellowish, translucent substance known as amber. If any insects or other organisms are trapped in the resin before it hardens, they can be preserved, often in exquisite detail. By studying these preserved organisms, scientists are able learn key facts about life on Earth millions of years ago.