Cheep Trick

It starts with a small, pale, ovoid container
Filled with a thin sticky liquid
And a roundish yellow lump
A hen sits on it
And warms it for 21 days
Or thereabouts
And then a chicken magically
bursts forth

What happened to the goo?
How did the chicken get into the egg?
Or are the chicken and the goo
Somehow both the same?
(unlikely as that sounds)

I still haven't figured it out
(I was just as mystified by
The caterpillar-butterfly trick)

I scratch my head
The chicken scratches dirt
Neither of us comes up with anything.