The metal gallium melts in the palm of a human hand.
Why it is true
The melting point of gallium is about thirty degrees Celsius. Since the human body temperature is around thirty-seven degrees, the heat of the hand is enough to turn it into a liquid.
Source: Royal Society
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.