Lichens chemically etch bedrock using acids that must be leached before eating

Evidence

Rock tripe is generally categorized as a starvation food, but it’s not so bad. My students and I make a pot every summer. Each thallus may take decades to grow, so our harvest is minimal, just enough to taste. First we soak the thallus overnight in freshwater to remove the grit it has accumulated. The soaking water is poured off to leach away the powerful acids the lichen uses to eat away at the rock. Then we set it to boil for half an hour. It yields a lichen broth that is quite palatable and rich enough in protein to gel like consommé when it is chilled, tasting vaguely of rock and mushroom. The thallus itself we cut into strips that are like a chewy pasta, making a quite serviceable lichen noodle soup. — Robin Wall Kimmerer, Braiding Sweetgrass, 1005

Categorization

• XREF: The Honorable Harvest ethic of minimal harvest connects to ch. 5 ‘gifts arrive unearned’ and ch. 44 ‘take only what is given.’ — connects to: Lichens colonize bare glacial rock over centuries where no soil can accumulate — Robin Wall Kimmerer, Braiding Sweetgrass: Indigenous Wisdom,…, 984