Piping Bags and Frosting

There is a company that makes piping bags
for making beautiful designs out of frosting.
These bags come with one of two nozzles:
square or circle.
(although sometimes combinations of both
may occur during manufacturing)

Frosting is made of all the shapes —
circles and squares — but also
lines,
rectangles,
triangles.
Shapes with any number of sides.
Enclosed.
Open.
Shapes formed into recognizables,
like letters,
numbers,
kittens,
stars,
a forest.
All these, and more,
somehow combine to create
the unimaginable beauty
and shape
of a soul.

Soul-frosting zips about the heavens,
so rarely bouncing off a planet, and nearly never
reaching ours and the piping-bag company.

Once in a very rare while —
say, once every 200 milliseconds —
the company will capture some frosting
right out of thin air,
and randomly assign it a bag.

Does the square or circle nozzle
(or sometimes a combination of both)
accurately represent the frosting within?
How can the frosting come out
not as the single shape of its nozzle,
but as the multitude within?