Mystery #3Tier 2-3cells / growth

Did you really start as a single cell?

You're made of around 30 trillion cells, more cells than there are stars in the galaxy. Yet every one of them traces back to a single starting cell. How does one cell become a whole person?

Microscope view of onion root-tip cells stained deep blue, packed in rows as they divide and multiply. — Photo: Adrián Horný, Wikimedia Commons · CC BY-SA 4.0 · via Wikimedia Commons

Your guess

What's your hunch about how one starting cell could turn into a whole body of trillions of cells?

There's no single magic word to type, have a go in your own words, then reveal the answer to see how close you got.

Make a guess to unlock the hints and the answer.