21亿年古化石显示地球最早活动生命体迹象

摘要：Scientists have discovered what could be the earliest signs of movement on Earth.They found string-shaped mucus (黏液)strands (缕)left by a slug-like (蛞蝓状的)creature crawling through mud 2.1 billion years ago in West Africa. The strands, found embedded (嵌入)in rock dug up in Gabon (加蓬).