Gram for gram, human bone outperforms steel in compression — a hollow lattice design gives it strength without the weight.
It has no nucleus, so it cannot repair itself. In that short life it makes roughly 170,000 trips around your body before being recycled in the spleen.
The epidermis renews itself continuously, and humans shed on the order of tens of thousands of skin cells every minute. Much of household dust is you.
Around 100,000 beats a day, pumping some 7,000 litres of blood, without a single voluntary command from you.
