At day 25 is it ok for one of my duck eggs to have a dark spot on it?

Question

I have 3 fertile duck eggs. They have all started moving. One is moving but, there is still a dark spot. is that good or bad?

Answer 1

Absolutely!

Answer 2

If the dark spot is one the outside of the egg it is a great sign!  It means that the duck has started to pip on the inside of the egg and you should be able to see a tiny crack in the egg soon!