@mouse935 a resin sack? Wth is that? Lol 
This is what it is. And its a preflower on the stem. The same one you use to sex the plant in the begining when it was little. Now that same flower is all grown up… boy aint it different now. I just pulled one of these off my king kong female im doing my other seed preservation run. Here look at it. It a little early to take the seed off the plant. But when im breeding new strains i periodically pull seeds as they develop to see how there coming along and i check other aspects like shell thickness, inside the seeds development inside. I take long tweezers to hold the seed and i cut the seed lengthwise with the scalpel and examine the seeds insides. I even purposely germinate prematurely developed seeds and test them but thats another subject entirely. Im always doing some weird testing.
This is just a quick drawing of a seed cross section.