I’m not putting any faith into it and still am disappointed I can’t see anything but I will give it a second chance before I toss it. It just strikes me as odd that there’s no sign of an air sac.
Yes, that's what make me think the porosity and the dark shell are just giving you fits. Because there "has" to be an air cell.
Have you tried different flashlights? The higher the lumens, the better.