What is that movement in your belly bottom feel like a heart beat?

The movement in your belly button that feels like a heartbeat is called a pulsation. It is caused by the aorta, the largest artery in the body, which runs from the heart down the back and into the abdomen. When the heart beats, it pumps blood through the aorta, which causes the artery to expand and contract. This expansion and contraction can be felt as a pulsation in the belly button.

Pulsations in the belly button are normal and usually do not cause any problems. However, if you are concerned about a pulsation in your belly button, you should see a doctor to rule out any underlying medical conditions.