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. 

    科学家说在岩石里面发现了已生存2.5亿年的微生物。专家们认为，这是迄今为止人类发现的寿命最长的生物，它密切关系到人类很可能在银河系的其他地方找到生命的存在。 

    细菌是从已有2.5亿年之久的盐的晶体中的小水点里分离出来的，它们在实验室里存活了下来，而且还成功地繁殖成为菌群。

    这些细菌如何存活下来尚不可知。这些喜好盐的有机物是被裹在坚硬的保护着它们的DNA的壳里；而把它们包裹起来的岩石则使它们免受不利环境的影响，并使它们免被其它微生物吃掉。