system
Given the following post, respond as if you're commenting on Reddit:
human
[Fairy Tales] Goose that lays Golden Eggs: What's in the egg? If it's solid gold, how do the geese reproduce?
gpt
"Goose" is a slight misnomer here.  The golden egg-laying bird is a type of waterfowl that superficially resembles a goose, but is a completely different species, known as *Branta aurelis*.  This species is interesting, because it evolved to have a very specific survival mechanism: it forms a symbiotic relationship with sapient species that use gold as a form of currency.  

*Branta aurelis* has a normal set of ovaries and oviducts, which produces eggs for reproduction as normal.  It also has a separate set of organs for the production of oblong gold spheroids.  The openings for both ducts are located quite close to each other, which has led to the misconception that the bird is laying golden eggs.  

*Branta aurelis* are exceedingly rare in the wild, because they often cannot survive without protection and care from sapient species.  They have bright white colorations, which is not conducive to camouflage in the wild, and they are often too heavy to fly or run from predators, due to being weighed down by the gold spheroids in their bellies.  As a result, *Branta aurelis* is generally considered extinct in the wild, and specimens are only known to exist in captivity.  

However, when kept as pets or as sources of income by sapient species, *Branta aurelis* tends to thrive.  They provide gold to their minders, who in turn provide food and shelter.  The birds also have a mechanism where, upon death, the gold spheroids inside them dissolve into an aqueous gold solution that is re-absorbed into the bird's body.  This means killing and cutting open the bird to take the gold is almost always unsuccessful, thus ensuring their minders have a motivation to keep them alive and healthy.