Mommy - where is the string?...

I have been looking at pictures online with my children to show them how the baby is developing and growing....Sebastian is really interested in pictures of him as a baby as well and very observant. So the other day he was looking at me, and around me, and up and down...so I asked what he was looking for? He was looking for the string because he wanted to pull it!! I asked what string - well it was the baby string ofcourse!! The umbillical cord - he was so funny...!