What is the tumor growth thing you found in your duck egg?

hi,

i asked the question.

i wann aexplain what i found.

we opened the egg and found a dark growth in it. its not fertilized (no male)

it looked like it was going to be soft but it was rock hard.

we cut it in two and it was dark red inside with a small cavity. it had a ''lead'' coming from it aswell.

duck ovaries look different so i don't think its that. cysts are soft. tumour would be the only explaination, but i don't think that's it, too neat inside and red to be a tumour.

it looked greenish on the outside, was covered in a whitish see-through film.

anyone have any knowledge of waterfowl anatomy??? (impossible to find pictures on the net)

any suggestions are appreciated.???

thanks.

PS. duck seems fine. happened a couple days ago.