Here is some encased ooze created from the Felwood samples you recovered. Take the case to Un'Goro Crater and find a pure ooze... the primal variety will do nicely. When you get close enough, release the ooze in the case, and let us see what the two think of one another. After the experiment concludes, bring me a sample of whatever is left over. I will await you here in the Apothecarium.