My two coturnix hens have been laying for about 2 weeks but have been consistent in the past 8-9 days. All of their eggs have been generally uniform in size. One of them has laid an egg that is different. It's bigger and heavirr than all the other eggs and has no speckles. It sort of a dirty yellow colour and seems to have a brittle shell. There is also a hole in the bottom of the egg. Any idea of what this could be?