In my handwritten diary the other day, I wanted to refer to a section of a book using the Section symbol. The attempt turned out to be something of a mess. I was doing it from memory, and my memory produced an image as of a 8 but with a little head on top. The symbol I was trying for in shown on the left, indicating that my memory was on the right track but now quite there. It is known as a double-S; indeed one person, known as Quora User, suggests that in handwriting one should try first writing an S and then another overlaying the first starting at about the mid-point of the one already written..
The double-S designation is also supported by its Latin designation, signmum sectiones—which, happily, provides the right sound as well. The mark is quite heavily used in legal documents but is otherwise essentially notable by absence in all other kinds of writings—unless one’s reading a nineteenth century work.