Discarded shell ?

Skinless in this shell I hide
Peering through the crack outside
I see enough to pass as real
I fool you too, I cannot feel

Inside my shell I live and breathe
Here my thinkings are conceived
I know there is a larger world
I lived there once,but back I’ve curled

I lie here like an unborn child
Listening to the sea so wild
Which other creature once dwelled here,
Discarded shell and knew no fear?

I see the trees and sky so bold
I hear the wrens,I see the gold
Will I ever come outside
When my true love lately died?