Dark spots - need help!

[Sidikore7]

So first time incubating - all the sudden this egg showed these dark spots. It’s almost a ring so thinking it’s a dud and I need to remove. Any thoughts?? Really appreciate any expertise! New to this but having a blast. Day 13.

 

[SpicyDill]

I don't see any veins. Looks like it's a potential exploder.