Is it normal that i have a...

Well, I can't believe I'm about to say this, but it's for the health of myself... so hear I go.

is it normal that I have a white thing in the middle of my nipples? (No, it's not liquid) What is it? Could I have cut myself accidentally of course, on both of them and it never healed and made a white thing? It's been there since I can remember.