Organisms a quarter－of－a－billion years old have been found alive and well trapped in rocks, says scientists. The discovery of the oldest living beings ever found has profound implications for the likelihood of life being found elsewhere in the galaxy, the experts believe. 

    The bacteria, which were extracted from tiny pockets of water trapped in 250million－year－old salt crystals, were revived in the laboratory and grown successfully into colonies. 

    Although it is not known how the bacteria survived so long, these salt－loving organisms are encased in tough shells that protect their DNA.Being trapped in a rock would have shielded them from adverse environmental effects――and from being eaten by other micro－organisms. 

    科學(xué)家說在巖石里面發(fā)現(xiàn)了已生存2.5億年的微生物。專家們認(rèn)為，這是迄今為止人類發(fā)現(xiàn)的壽命最長的生物，它密切關(guān)系到人類很可能在銀河系的其他地方找到生命的存在。 

    細菌是從已有2.5億年之久的鹽的晶體中的小水點里分離出來的，它們在實驗室里存活了下來，而且還成功地繁殖成為菌群。

    這些細菌如何存活下來尚不可知。這些喜好鹽的有機物是被裹在堅硬的保護著它們的DNA的殼里；而把它們包裹起來的巖石則使它們免受不利環(huán)境的影響，并使它們免被其它微生物吃掉。