You May Be Younger Than You Think

Some parts of you may be mere hours old

Throughout your lifetime, your body will go through a lot of changes, and we aren’t just talking about your awkward puberty years.

Over time, almost every cell in your body will turn over, helping to create a (sort of) brand-new you. Your fingernails, for example, are new every six months. Every four months, you get a fresh, new blood supply. And the cells in the lining of your stomach replace themselves much more quickly—every two to nine days.

But what remains with you throughout your entire life? It turns out, only a few cells decide to stick around. According to a YouTube video posted by NPR Science, only half your heart and the core of the lens of your eye remain with you from birth to death.

Check out the video above for more amazing body facts. And hey, maybe now you can start celebrating your birthday way more often.