im not an expert but i have eggs in the incubator and the ones that had a black spot in it was a good thing cuz now their alive moving around inside my egg shells!!! i cant wait friday is 21 days, so yah i believe thats good!!!! yah!!!
Yes, this is good. That is the embyo developing. Through the eggshell it looks black but I bet if you cracked that egg open, it would be a little red spot.