Mountains will crumble and temples will fall, and no man can survive its endless call. What is it?

Why this works

This riddle cleverly highlights the unstoppable and all-consuming nature of time. The phrases "mountains will crumble" and "temples will fall" suggest that no matter how strong or enduring something may seem, it will eventually be worn down by time. The "endless call" refers to time's relentless progression, emphasizing that everyone and everything is subject to its influence, ultimately making the answer—time—perfectly fitting.