The poop fertilized plants, the plants were harvested, some of them were turned into bread, others fed a pig, and that's what you're eating. Some of the poop decayed and was released as gases into the air, which were then recaptured by the plants, by bacteria in the roots of soybeans, and by Haber-Bosch factories (confusingly also called plants) which made synthetic fertilizer to fertilize the plants further.
You are recycling your sandwich, made from poop, into more poop.
This is the reflection on the disgusting nature of food and its link to the interdependent arising of all things. Your existence is inextricably linked to the existence of the pig and the poop. They are not separate processes; they are different focuses in the same process.
"The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of star stuff."
—Carl Sagan
FWIW: Sagan was poetic but the intuition turns out to have been wrong. Models are still not super convincing, but supernovae alone aren't enough to explain the abundance of heavy elements. A big chunk of the rare earth nuclei we apply in industry today seem likely to be tiny remnants of neutron stars that were thrown off in a merger event with another neutron star or black hole.
Thanks for bringing this up! I was always curious and decided to research it. The graphic at the top of this Phys article describes the origins of all elements on the periodic table. It claims that only a small number of elements were remnants of neutron stars, however. https://phys.org/news/2020-09-elements-neutron-stars-contrib...
>Half of all the elements that are heavier than iron—such as thorium and uranium—were thought to be made when neutron stars, the superdense remains of burnt-out suns, crashed into one another. Long theorized, neutron star collisions were not confirmed until 2017. Now, however, fresh analysis by Karakas and fellow astronomers Chiaki Kobayashi and Maria Lugaro reveals that the role of neutron stars may have been considerably overestimated—and that another stellar process altogether is responsible for making most of the heavy elements.
(Though the atomic nuclei didn't originate in the poop; they were just passing through. But cobalamin molecules, for example, do originate in poop pretty often.)
HAMLET
Not where he eats, but where he is eaten: a certain
convocation of politic worms are e'en at him. Your
worm is your only emperor for diet: we fat all
creatures else to fat us, and we fat ourselves for
maggots: your fat king and your lean beggar is but
variable service, two dishes, but to one table:
that's the end.
KING CLAUDIUS
Alas, alas!
HAMLET
A man may fish with the worm that hath eat of a
king, and eat of the fish that hath fed of that worm.
KING CLAUDIUS
What dost you mean by this?
HAMLET
Nothing but to show you how a king may go a
progress through the guts of a beggar.
