shallow

Perhaps you've seen the inverted water bottles used with cages for rabbits, hamsters, and the like. The bottle feeds a steel tube, which is sealed by a small steel ball.  The animal, licks the bearing, lifting it, and a little water flows.  Click click click is the sound as the little ball falls back into place between licks.  A little steel click click click.  That's what I hear when I click my mouse at work - the same clicking.  And really, as a I read through the news online, what's the difference?