egg stuck to fin of male goldfish

[CrisCar]

So, I'm not interested in breeding my goldfish at this time, but I noticed my male comet has a large goldfish egg firmly stuck to the top of his tail fin, in a very delicate spot where there is a slight fork in the top of the tail fin. It may be too soon to tell but there's no indication at this time that it's a viable egg (and no other visible eggs in the tank, so I assume they were someone's lunch). If it's not a viable egg, is there any harm in just leaving it there, or could it rot and cause problems for my comet? Thanks for any advice. I have not yet been able to get a clear photo.