Chickens are obviously the best pet, they:
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Poop free eggs
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Eat your leftover vegetables
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Poop free fertiliser for your garden
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Are good alarm clocks
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Make hilarious sounds
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Are stupid looking
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G*mers get their own real life Chocobos
Chickens used to be a staple of the home during the great depression. Most working-class people from the silent generation had chickens to give them free eggs. Chickens are the pet of the proletariat.
The entire reason the rich don't want you to be able to afford a house with a backyard is that they don't want you to figure out how awesome having chickens is.
Obviously your practice of eating eggs from your chickens is ethically way better than eating eggs from an industrial farm. At the same time, it is a bit exploitative to take and eat your chickens egg, which simply is not produced for human consumption. Think of how people adopt dogs without any expectation of the dog providing anything in return, why should your relationship with a chicken be any different? Not a chicken expert, but I've heard from others that allowing your chickens to eat the eggs (and shells as well) is good for them because it replenishes some of what they lost producing the egg (especially calcium).
I don't expect anything in return, they just happen, lol. I do crush up the eggshells and feed them back. Like you say it helps give them some calcium back.