Bones of the skull have a few lines in between them, that are called sutures. Wiggly sutures of the skull are not looking long but they are long. Well, no one could measure the actual length of sutures of the structure of the human skull. Sutures are so tiny wiggles that can not be measured by tape as we measure other bones. Moreover, if you use thread to measure length, you have to be very keen to arrange thread on the zig-zag pattern of the wiggles because they are very tiny. Then, measure the full length of the thread. Well, this threading method is not accurate because when you check the suture wiggles under the microscope, you will find that tons of them are missed. So, mathematicians can measure the length of the suture as they are fractals.