What Do You Mean by Stone Soup?
Starving people can be pretty creative at finding food—even eating the crust from rocks. Lichen called rock tripe makes an unusual soup, and another bitter lichen gives Icelanders a nutritious flour.
Lichen is actually two kinds of things growing together—fungi and tiny plants related to the seaweed. By teaming up, they thrive where very few plants can live.
They are edible when properly prepared and have been used as a famine food in extreme cases when other food sources were unavailable, as by early American northern explorers. Actually, rock tripe fed George Washington’s starving troops at Valley Forge.