What is wrong with my egg?

I'm pretty experienced with incubating chickens in the past, but this is my first round in the duck world and I have a concern for one of my eggs. They are mallard eggs, and today is finishing out day 23, so the big hatch date (hopefully easter) is right around the corner. I have 6 eggs total, and 5 look absolutely perfect and right on track for hatch day, one egg is a bit odd though. On one side of the embryo looks fairly normal, including veins around it, and some fluff, but when you flip it over there is literally nothing. No veins, and an odd wavy oval going around where the embryo is. I initially thought that the chick was dead and it was a blood ring, but it moves on its own and twitches around just like the others. I was just wondering if anyone has had something like this happen? and so close to hatch date I'm just hoping the poor baby will be alright :c

Is @Orca5094 or @Lacrystol around?

It looks to be underdeveloped, which means it just hasn't developed like it should for some reason, and may not make it. :/ This can be caused by many things, like a genetic issue or a deformity of the duckling.

You should of course leave the egg in the incubator for now and see what happens, though. Sometimes eggs will surprise you and hatch when you don't expect them to. I had an egg last year that was behind all the others for the entire incubation. I was sure it would never hatch, but you know what? Four days after the first egg hatched, I saw a pip on that "dud" egg! I had kept it in the incubator because it was still alive somehow. She hatched out and is now almost a year old. Beautiful duck named Ginger.

Having said that, I've also had a few "underdeveloped" eggs that did not make it to hatch and died in the shell. With most of those I saw the ducklings were deformed in some way when I opened up the eggs to investigate (I suspect bad genetics in those cases as they were shipped eggs). Anyway, there is usually a reason they do not make it to hatch.

So I guess my point is: be prepared for that egg not to make it, but don't give up on it, either.

Update!!!
The funky egg has started to catch up in development, so I'm starting to breathe again haha. Last night was day 24 going on to 25, and I noticed when candling that one of the babies was about to break into the air sack, so I slept on the couch next to the incubator to be safe. Of course, it ends up I was woken at 4 AM with some odd sounds to find two of my most active eggs had been rolling around the bator xD Candled them and both were soooooooo close to puncturing the air cell. I went ahead and just put them on lockdown since it is day 25 now technically. Day 25 seems fairly normal for beginning pips if the incubation period is about 25-27 days I assume. This feels so different, whenever I hatched chicks, I feel like they always hatched spot on day 21 haha. I just put them back into positioning with their beaks facing upward since they had literally rolled from one side of the bator to the other haha, I also took photos to compare in the morning if they move again! If there is any significant moving I'll make sure to post pictures! Thank you so much for the help!!!

That's great to hear! Hope all goes well with your oddball egg!

Yes, this would be a good time to start lock-down. Ducklings take their sweet time hatching, the key is always patience with them. They typically rest about a day in between hatching steps (internal pip, then external pip, then "unzipping"). So, it will likely be a few more days before you see your new babies pop out, but be sure to come back and post pics and an update! ^-^

Thank you so much and will do! Keeping my fingers crossed on all of them!

Well I'm pretty sure that the odd egg passed away :/ I saw some promising wiggling from it yesterday, but today absolutely nothing and when I candled it, there was no movement or veins. I'm pretty sure he was able to press up against the air cell but couldn't get through. I'm going to give him until Tuesday or Wednesday probably, but I'll most likely end up doing an egg-topsy just to see what happened

Sorry that one didn't make it. :/ Definitely do an egg-topsy and see if you can figure out what went wrong. Sometimes it's nothing we can see, but other times it is something obvious like a malposition, deformity, or even the embryo getting stuck to the side of the shell (that one is more a problem with embryos that die early on in incubation).

Good luck with your others, though!

The first guy to hatch! We had 3 hatch on Easter and we have one more on the way today! Out of 6 eggs we got 4 ducklings total, which I'm actually over the moon with since we ended with a 68% hatch rate on shipped eggs!

Aww, he's a cutie! ^-^

That is a very good hatch rate for shipped eggs, so congrats to you! I tried shipped eggs once and had about a 7% hatch rate. Needless to say, I never tried it again. I had 100% hatch rate last year with my own eggs.