To behold the sight of a purple worm means that in all fairness it was too late for you. The purple worm is a large, armored worm.  Growing up to eighty feet in length and weighing up to forty thousand pounds it is by far a massive creature. Its large mouth is filled with rows of razor-sharp teeth, and if that is not enough to scare you, it also sports a large bulbous stinger for a tail.
 
It moves underground eating everything in its path, in search of food. Such creatures are indeed a fearsome threat to those who farm or live in small villages.  If one awakens from its slumber and begins to attack settlements. Then adventurers are called, and the worm is dealt with. Such actions provide an ample opportunity for my apprentices to collect the poison and bring it to you. Corked and sealed in a vial, to preserve its potency. Sufficient for all magical potions, magical studies, and spell components.