infinitesimal

A non-zero quantity whose magnitude is smaller than any positive number (by definition it is not a real number).

Incalculably, exceedingly, or immeasurably minute; vanishingly small.

“Do you ever get the feeling that you are but an infinitesimal speck, swallowed by the vastness of the universe and beyond?”

Of or pertaining to values that approach zero as a limit.

Very small.