What Is This Fuzzy Stuff?

Ever since Ellie was first born I have run my fingers through her hair (what little there is of it) while I nursed her. Now when Ellie is sleepy she will rub her head with her hands. This morning as she was rubbing her head, she discovered that she has hair. She began grabbing onto it and pulling. Now she is fascinated with it. Hopefully she won't pull it all out... she's worked so hard to get the small amount of hair she has!