VOA慢速英语:地球上最早的活动有机体生出现在21亿年前

fossil – n. something, such as a leaf, skeleton, or footprint, that is from a plant or animal which lived in ancient times and that you can see in some rocks

deposit – n. an amount of a substance, such as oil or coal, that exists naturally in the ground

astonishing – adj. causing a feeling of great surprise or wonder

diversity – n. the quality or state of having many different forms, types, ideas, etc.

metabolic – adj. of or relating to the chemical processes by which a plant or an animal uses food, water, etc., to grow and heal and to make energy