Aminita "death cap" mushrooms are one substance that I know of that remains toxic after exposure to high heat over time. "Amatoxins cannot be destroyed by any

Aminita "death cap" mushrooms are one substance that I know of that remains toxic after exposure to high heat over time. "Amatoxins cannot be destroyed by any conventional cooking method, including boiling or baking. Freezing or drying the mushrooms also fails to remove any amount of amatoxin..." https://slate.com/technology/2014/02/most-dangerous-mushroom-death-cap-is-spreading-but-poisoning-can-be-treated.html https://slate.com/technology/2014/02/most-dangerous-mushroom...