Do our belly buttons consist of scar tissue?
The place where the cord was cut do not stay with us - it falls in a week +- after the birth, while the umbilicus is the only visible natural scar formed by natural processes, not by gynecologists:



Multiple sources say the umbilicus has a scar tissue in it.


  After birth the umbilicus is the only naturally formed visible scar on
  the body.


Br J Plast Surg. 1998 Oct;51(7):538-41. Umbilicosculpture: a concept revisited.


  Umbilicus is a scar, which is the place of the previous merger of the
  fetus with the umbilical cord.