We've had a couple similar to that, laid by the two biggest of our golden comets, Tibet and Golda. Scary huh? I keep checking to see they aren't eggbound, but they seem to make these easily, here's hoping...
Pullet egg on left, today's humungo on the right. Pullet egg is 5 cm long.
If you have access to a dremel tool you can drill a hole in the bottom. Thn take a syringe with the needle and pull it out all the way so it's full of air,and stick it in there and push all the air in the egg.the pressure pushes out the yolk it's very easy and clean. AND it's only one hole. good luck!