(lively music) - Hey, cool cats, I'm Dr. Universe here to answer your baffling science question, like this one.

Are we always growing?

When I was a kitten, I used to keep track of how tall I was getting.

I'd make a little pencil mark on the wall, right above my ears.

We might not be growing taller every second but parts of us do grow all the time.

We grow new hair, fingernails and bone, we even grow new skin.

Skin is the body's biggest organ.

It helps protect us.

If we use my microscope, we can even see some of these cells.

Look, there are some now.

Our skin cells die and grow pretty quickly.

About a month from now, you'll be in a whole new layer of skin.

As long as we are living, our cells are dying and our bodies are making new ones.

You can submit a science question of your own at askdruniverse.wsu.edu.

(lively music)