dark eggs (Marans ) plus white tiny eggs questions

Hello dear BYCMember that is reading this ,

A little while ago my passed away Maransgirl had some fertile eggs she was sitting on , I putted the half of them in a homemade incubator with ceramic heatlamp , thermosthat , humiditycontrol , ventilation , etc ...

Now a little while after that one of my other hens was willing to hatch so I gave them to her , turned out she had a problem in fact , she really was a broody yet she started to eat all eggs she could get , so again all eggs into the incubator , there were only a few of them left , now I found out a three days later that I had been quite unlucky with hatchingeggs , incubator didn't heat up anymore due a technical problem ( I am still a woman ? ) , now I believed it was hopeless after fixing but I had to put in some hatchingeggs from some Old English Games so I left the eggs in , the eggs have been icecold tough today I did that thing with a lightbulb , to be honest I was not really sure what I was looking for but since lots of people say how to and show pics of it I wanted to see inside of them , so what did I see ?
Some of the eggs I called ' dead ' are getting a bigger dark shadow , so there must be something growing in there I assumed , also few eggs have a funny dark spot in them wich is moving a bit , on many of these eggs I could not see anything , also no dark spots only that the yolk is growing ( as if there is a shadow inside of it ) and two eggs didn't have that big yolk so I am sure there is atleast a difference .

please note that some eggs were putted in almost a week later due onather hen that seemed to have been stealing eggs and she hided them VERY good , so I found them only a half a week orso later and putted them in anyway since I don't know she did sit on them or not .

Now the eggs I putted in from the Old English Games are better to look trough , tiny or average sized better yet , and light colour I was able to see the same as in the other eggs but this was a lot bigger , I mean that dark little spot looked really big in comparison with the dark thick shelled eggs from my marans girl and they did not all seem to have that spot but they also did have like the Maranseggs dark shadow inside that has gotten bigger , besides 2 eggs , they looked just like an egg with a normal yolk ( just a yellow/reddish yolk showing same size as when I open up an egg .

Now I would like to know that that dark shadow actually means those eggs are still devoloping or just get bigger due the higher temperature or (what cause it might be ) , especially from the Marans because I honestly have never done this before , secondly I do not own a professional lamp to do so and third I don't have the slightest clue what it all means and that shell is so dark and thick I barely or not see anything , same question is with the eggs that are better to see trough with the shadow that gets bigger , is this development or do I have to toss them out ?? they do not all show that spot I saw on picts , some dark eggs showed a veryyy tiny one but further i don't see it so can anyone just tell me when there is only a shadow that is getting bigger the eggs are still likely devoloping into a chick or not and why do I have in the dark eggs only a very tiny dark spot and in the white a huge one ?? what does that btw mean ? I honestly believe there is life inside of a few of the marans and a few of the white but I am totally new into this and it is probably more hoping they develop instead of in fact having that happening .

Hopefully anyone that can explain these differences

What days are your eggs on of incubation? What you should be seeing inside depends a lot on what day they are on. In general, for about the first week all there really is to see is a little spot with lots of blood vessels around it; usually it takes up until day three or four or even five to be able to see even this. In the second week, the chick should get bigger and you should be able to see the dark spot that is the eye, especially with lighter eggs. As development progresses more the chicks will start moving around as they and their blood vessels get bigger, until in the last day or two the whole egg besides the air cell should appear mostly dark.

hi thanks for the reply ! so I can see their eyes ??? awesome haha ! those are big eyes lol but why do i not spot the bloodthings then ?? I only see black spots and eggs that are filling up with their yolk having eyes . Ok that sounds even creepy but the date , the date , uhu good question , I did write that down because all the changes they went trough but I need to get upstairs for that because I keep caresheets about all chickens and there is an extra sheet when the eggs were being hatched for the first days by the hens and how long they stayed apart and how long in the cold and the temp , everything is written on that but can't get that now , going to get that ! and really thanks for explaining !!!

I didn't have the chance to get my sheet earlier so now I was and had to figure some things out because not all eggs are from the same time ( they are in a large incubator and I keep it marked with different kinds of signs )
So this is what the egg-situation is :
I was sure I putted in more eggs from under the hens but it seems I tossed them out a lot because I was convinced those were no longer viable .
The eggs in the incubator are now on day 16 , wherefrom the half of it is already on day 19 .
Some other eggs are in for now 10 to the 11th day .

Now the eggs I was talking about do not all have that big black spot , some have it and when I checked today I noticed some eggs are heavy ! but i was unable to see anything at all besides that the eggs have become heavier and are very dark , black inside , is that a good or a bad thing ?? I assumed that due the weight has gotten definitely up the chick might have been developing more ? Is that a wrong idea I have or is this correct ?
Also why are they now so hard to spot ?? this is impossible to look trough now , unless you have the professional equipment but I doubt you'd see much .
Now the eggs from day 16 and 10-11th are different but I'm worried there is a problem because at first I could see the chick inside moving when I turned their egg and now they stay on one side ??? are they stuck ??? Is there anything i can do about that ?
I do turn the eggs three times a day so I found it a bit odd that they are stuck , or is that not being stuck but just the place they want to be ??
Some eggs are not showing the same big amount of black mass as others and they also feel very light .
So I also candled them with a normal lightbulb and looking trough the eggs without heavy weight I see the egg looks empty ?
And the ones with the heavy weight are just not to be seen inside besides an aircell you see nothing at all .
The youngest eggs show the yolk getting bigger and also dark coloured , besides 1 that has just the same size and color as a regular egg ...
Any good about this or did I lose them ?
Some eggs also seem to have moved on their own ! I am sure how I turned them , now few eggs were laying different , not on the x , nor on the o but between that and nobody can touch them ???

I did already put up the humidity but I just do not know anything about the chicks inside and I really feel like there is life inside but that there is something wrong .
Pretty much worried and hopefully these babies are not in pain !
Any explanations would be very great I would be greatfull and I think the chicks , if they are alive too !
Ty

3 weeks ago I hatched 28 marans eggs. After I backed out the 8 infertile ones, 3 that pipped in location other than the air sack and the one late hatcher that wasn't right I had 100% hatch. After the first week I would randomly candle the eggs every 3 days. During the entire incubation I never could see anything through that thick dark marans shell. I really couldn't see anything different during the last part of the last week. I removed the chicks and the ones that died pipping but the late hatcher and infertile eggs remained until the 23 day with no problems.

Leave them be. A decision now may result in a big disappointment when you open an egg to see where it stopped development and discover it was still viable. Leave all those questionable marans eggs in the incubator until 2 days after they were supposed to hatch. Better to be safe than be disappointed. Better to have one than none at all.

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so they have this in common ! actually that is more good news to me because I really believed it was a problem , especially if I compare them with the white smaller eggs you start to doubt it very much and yet I do turn them ( also more randomly but let's say I keep them in ' movement ' ) and also the temperature deflects a little bit but it is never too hot or too cold actually , it deflects from just one ° Celsius on and off so I noticed it is also happening with even professional incubators and humidity measures always correct so I just didn't know for sure . But it is as you mention that that thick shell is so difficult ! I'll just have to let them be indeed and it will be like a kindersurprise egg ;-) . Just a question about what I really wanted to know : about the weight that seems to be more , is that how it should be / goes with any hatches ?? Because that is the one thing I know for sure , most of them weigh much more ! when I took one to see I right away said " OMG they are heavy ??? what is this ? " lol , same happens with the ones that are not from my marans , the tiny white ones are also more heavy but only the ones that show obvious signs there are changes happening , gaining weight and having a clear black spot with lots of webs around it and one egg even showed movement once so those are probably going to hatch but those Marans girls know how to surprise you in fact ! They have great eggs but for hatching , especially first time it is not the best to start with I think . Keeping you posted !! I'll show pics if they hatch because I am waiting for them IMpatiently a good stressmoment in fact . I'm so feeling like kissing the eggs and say " hatch out hatch comon you can ! " Already have a box ready for the chicks if hatched and made a food and waterdish so all is prepared but those shells arghh BTW : a congratz on your great hatch !!! lovelyyyy

Never weighed mine one time. First 18 days I kept humidity between 25-35% except when it was raining and ambient humidity was 100%. When I turned the turner off I filled the water channels and pushed it to 65%. I don't have time to become so obsessed with this details. Everything a chicken knows about hatching a clutch is encrypted in their genetic material. Their eggs get cold when they get off the nest, some are warmer others cooler depending where the hen has jostled them to. Some hatch some don't. Overall I think we humans over think things way to often. Our original cook stove had the old school pilot lights. My kids and I hatched a small clutch of eggs in a cardboard box over that pilot light on the stove. 25% hatch rate. The only thing we knew was they needed to be turned and I'm fairly certain some days they weren't turned. As humans we tend to over complicate the process.

Btw, weighing the eggs is done to ensure the air sac is getting bigger. (Too much bother for me. )