Chicken maybe? It would represent an egg that did exist, but now doesn't.
Now I want some chicken & waffles
https://en.wikipedia.org/wiki/Chicken_and_waffles
Also, in the other direction in space time, it's an egg that could have been, but now won't.
Now I want some chicken & waffles
https://en.wikipedia.org/wiki/Chicken_and_waffles