The shell bone script of character Nine
There are many explanations.
1, an arm with a hand of person
2, a brooked cave or hole
3, a kind of snake or dragon.
No matter what, most people agree that it explores an unknown area by reach as far as possible. I prefer to the arm with open hand, trying to explore an unknown deep cave.
The bronze script of the character is
Which may be an arm, a snake or dragon, a hole, same as the shell bone script.
To me which is like a person kneeling down, and his head and arms stretching forward, searching something.
The big seal script of the character
Same as clerical script.
The Pinyin of 九 is Jiu3.