Tiny rotating hairs inside a microscopic cavity decide where your organs will grow

Heart to the left. Liver to the right. That's where you'll find these organs in a healthy human body, but surprisingly, in some people, the heart is on the right and the liver on the left. This normal or abnormal asymmetry can be traced back to your embryonic stage. In the early days of your development, a small fluid-filled cavity known as an embryonic node forms in your embryo. Inside, tiny micro-hairs known as cilia create a flow pattern that steers where organs grow in your body. However, the science behind this flow process has remained a mystery until now.