fossil  
noun [ C ] uk/ˈfɒs.əl/ us/ˈfɑː.səl/
  (IN ROCK)     
  化石
the shape of a bone, a shell, or a plant or animal that has been preserved in rock for a very long period
   (PERSON)     
 informal humorous老人;(尤指)老顽固,思想僵化的人,老古董 
an old person, especially one who will not accept new ideas