Just when you think you know everything there is to know about the human body, you learn something new. Take, for example, your heartbeat. You know it changes, but did you know it can change to imitate the music you listen to? A video uploaded by What The Facts brings us 25 interesting facts about the human body that may blow your mind.

The heart is by far one of the most interesting organs inside the human body. The heart, which rests in the middle of the body and not the left side, creates enough energy every day to drive a truck for 20 miles. Due to its own electrical impulse, the heart can keep beating even if it’s separated from the rest of the body.

What’s the deal with iron supplements? Is there really metal swimming around our body? Yes. In fact, there’s enough iron in the human body to make a 3-inch-long metal nail. There’s also around 4 pounds of collective bacteria in the body. Our mouths are home to more bacteria than there are people in the world.

What are some other interesting facts from this video that may have surprised you?