Mushrooms like Boletus sensibilis bruise blue almost instantly when touched. Some are edible, but others can be toxic. https://video.nostr.build/ee191b216abf31e09e1c26ce059101ad892b6f66ac34df45bcfff68d11f42af8.mp4
Discussion
Imagine a wizard 400 years ago
Splitting it in half, looks to you in the eye, and tells you if it went blue you are dying today
Unless you gave me such and such...
it would work on me like a knife in butter 😂😂