A "nest egg" was originally a ceramic egg placed with chickens to encourage them to do the right thing in the right spot at the right time.
We found this one years ago when we were demolishing an old chicken run. beside our back sheds.
It has sat in the kitchen since then but today I was testing out a new little lightbox and decided to use it as the guinea pig, to mix metaphors.
Perhaps I am also making a point of course. I wonder who keeps the Tory nest eggs and if there are any in Downing St....