I started using Blender a few weeks ago and right now I'm starting my first project without a tutorial. I'm starting to create a character and the first thing that came to my mind was "It needs to have symmetry", so I used a Mirror modifier on my object and it has this "seam". In the image I used a Sphere because it is much more noticeable.
So, how can I fix it? And why does this happens?
Clip
in the mirror modifier's settings, to 'prevent vertices from moving through the mirror plane' (blender.org/manual/modeling/modifiers/generate/…). $\endgroup$