Is this Duck egg fertile??

[MartinFamilyHomestead]

I do not believe this egg is fertile but curious on other opinions? Do not have much experience with telling if they are as I never needed to know. Last year we did look into it just out of curiosity and you could very easily tell that the eggs we were collecting were fertile. What are your opinions on these? We are looking at selling fertile hatching eggs but want to wait and make sure majority of the eggs we are collecting are fertilized.

 

[cheezenkwackers]

Looks infertile to me.