<p>I am old.</p>
I keep a finger over the "block" button at all times. Which isn't to say that I block anything I disagree with - but some people just show their colors so fast.
Based on the posed question and its limiting conditions, elemental mercury is a correct answer.
If you include materials which are liquid outside of "room temperature," things like magma and liquid nitrogen would also be correct answers.
Elemental mercury.