Riddle
I have traveled quite far and wide
through many users, big in size
at least to me, but I provide
the value that man itself prides.
Spherical in shape, I can fit,
inside the narrowest cracks,
to get me you have to always commit,
to your career, it makes the big impact.
With a head but no feet,
and a rear that squirrels have,
can withstand the harshest heat,
and stands for a half of a half.