A few years ago, I only had two of these on each shoulder. They are red "grooves" on my shoulders (they are concave), and they are long (2-8 cm) strips, not very thick. They are less than 1 cm deep but they do go into the skin.
They do not hurt or itch, though it does concern me that I have been getting more and more recently.
1) what are these?
2) Are they harmful and how do I remove them?