[spoilers, obviously]
It's an item split in three pieces, two you pick up in the fleshy section where you need to cut off the bile obstructing the jump, the last you get in the Oracle chamber.
You can give it to Tayn once you come back (I thought you could give it to Llengrath as well, but she leaves immediately with no option to give it to her? Not sure if it's a bug or something) but the ending slide about it was kind of a letdown, not sure if you can get other results by making different choices.