Acromantula Venom
From UnknowableWiki
Acromantula venom is a rare and very valuable substance. It is probably used as a potion ingredient. Because it is almost impossible to collect venom from a living Acromantula and the venom dries out shortly after their death, a pint can fetch up to a hundred Galleons (HBP22).
When Horace Slughorn hears from Harry Potter that Rubeus Hagrid's pet Acromantula Aragog has died, he immediately thinks of the venom to increase his meagre salary. He attends the funeral and collects quite a lot of venom while he pretends to admire Aragog's head. This put shim into a very good mood, which, in combination with a lot of wine, helps Harry to get his memory of Tom Marvolo Riddle (HBP22).

