So, you think you know your own body so well it can't surprise you. In fact, there are many unusual rare facts about yourself you might not know but will find out now. Your brain will grow by roughly 2% if you venture into space. Our belly buttons have an entire animal encyclopedia in them, with a range of about 70 different bacteria. Only about 43% of you is you: you're over 50% tiny little creatures that mainly live in your gut and other body parts without ever leaving it.

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