There’s a fastener on the back of the saddle, where the seatpost joins the saddle. What does it do?
It’s job is to get in your way.
It has done a good job then!
No, it helps to prevent the seat post from sitting flush on the seat base.
I never understood this design …
It seems to me to be a leftover from earlier revisions of the saddle where the cover was removable.
Have a look here…