The writing material of coral post is very special. Bamboo paper is light yellow, and there are many bamboo fibers on the paper. It is said that this is the earliest work written on bamboo paper found so far. The title of the post is: "Accept the King of Zhang Sengyou with the inscription of Yukime. Yanerwu, obtained by Yuan Zhi in the old place. I also received a quiet courtesy picture and a painting of the Six Dynasties. A coral (draw a coral pen container with the word "golden pedestal" next to it). Cao Zhusan's expenditure comes from Jinsha, which comes from heavenly stems and festivals. I was honored to pre-name the watch that day, and I was ashamed that there was no five-color pen flower. " The Coral Post is widely circulated. Guo Tianxi, Ji Zongyuan, Xiao in the Southern Song Dynasty were collected by Liang Qingbiao, Wang, An Qi and Pei in the Qing Dynasty and returned later. 1956, Zhang Boju donated the work to the Cultural Relics Bureau of the Ministry of Culture. There are descriptions of coral branches in books such as Moguan, Wonders of Life, Passing Clouds, Grand View Record and Zhuang Calligraphy and Painting Record.