老蚌生珠

Explanation: Yin old son with the original metaphor. That old age after a son. 　　Source: Han Jung "and Wei-side book" near the old clam unexpectedly lacoste, even precious. "" Northern Qi Lu Yang Chuan book, "I then out of the Big old pearl mussels." 　　Examples: See bear brown bear has been a dream, the line to see ~. (Bi-Ming Zhao, "Mr. Peng Lai Chuan")