Sporulate Sac in Warframe is a resource that can be obtained from fishing for the Glutinox fish on Deimos. All fishing on Deimos is done through Daughter, so make sure you visit her and purchase the Spari Fishing Rod for 500 Standing, as it will make fishing on Deimos a little easier.
The Glutinox can be caught outside on the Cambion Drift in rivers and will spawn during the Vome cycle. They have a better chance of appearing in the presence of Fass Bait.
How to get Fish Bait
When Fass and Vome duel in the Cambion Drift, the losing Wyrm’s body will be blown to pieces, scattering residue across the map. Both of these residues can be picked up and used as Bait for the Infested Fish and can be accessed in the fishing menu. To open the fishing menu, just equip one of your fishing spears. Fass bait is the red/orange colored residue.
How to use Bait
You will need to drop the bait into the water that the fish flow through when they are not floating through the air. You cannot catch the fish when they are in the water, and can only do so when they are floating.
How to process fish on Deimos
You can bring your fish to Daughter, located in the Necralisk, and marked on the minimap by a small fish symbol. You can cut the fish here and trade in parts for Daughter tokens that you will need to rank up with the Entrati Syndicate. If you cut up the Glutinox, you will get Sporulate Sac, Ferment Bladder, and Benign Infested Tumor. No matter the size of the fish, you will only ever get one Sporulate Sac from them.