I always wondered what these things were. I had a ton as a small child. My dad always said that they were the beginning stages of moles, but they disappeared in middle school.
My mother attended nursing school in the day and worked in the dye house in a textile mill at night when she was pregnant with me... so, lord knows what I was exposed to in utero.

This really works perfect.
https://www.youtube.com/watch?v=S7LyrN20i3Y