Those are aborted ootheca that never fertilized or never retained until hatching. That happens when the roaches are under stress from too little or too much of something- food, water, air circulation, too dry too often, too hot or cold, etc.
I'd really like to know what the problem was. Here are the parameters: They had no substrate, but they haven't had any for the last 15 years in their original colony either.
Temp is 78-80 at night and I let it creep up to 85 on a warm day.
Food is a premium chicken and rice based dog food constantly available, floating turtle sticks( dry, in a little lid ), and at least one fruit or veggie (usually carrot, yam, orange or apple) at all times. Plus occasional bell pepper, banana, wheat bread, romaine, monkey chow and other stuff like that.
Clean water crystals at all times.
I also mist them once a day or twice if its really hot and dry. I spray the lid heavily and then the sides and lightly on the six egg flats. The droplets are mostly gone within 3-4 hours.
This is the same routine for all of my species and all the others seem to be doing great. Blaberus fusca and discoidalis, Blaptica dubia, Blatta lateralis, G. portentosa, E. posticus, and A. tesselata. My giganteus are just nymphs, but seem healthy to me. The giganteus and tesselata are on the same substrate that I just moved the craniifer to. Everything else has no substrate. I'm planning on moving the fusca to substrate soon.
Maybe I just mess with them too much. I crack open the lid to check the water crystals and food every two or three days. These craniifer seem really flighty and nervous. More so than my other species. I peel apart the flats to check baby status every 7-10 days. My roach room gets minimal foot traffic. The door probably gets opened 3 or 4 times a day except when I'm doing a project in there. (Like building new shelves or setting up new tubs)
I know its impossible to tell for sure over the internet, but any insight will be greatly appreciated. Sometimes, it seems, the tiniest little tweaks can make a big difference. There were about 30 of those aborted ootheca and it just kills me to think of how many babies that could have been.