A few days ago Sophia found a ball of tangled, screwed up hair. The sort of thing you might find in the shower after you wash your hair, or after you've combed out a child's plaits.
Anyway, she said "my hair!" and brought it to me quite distraught. She wanted me to help her to put it back on her head! I had to take a very long time explaining to her that hair grows, but then when it's getting too old it falls out and new hairs grow to replace them. She was eventually comforted, and allowed herself to put the ball of hair in the bin.