Rock tripe is the common name for various lichen of the genus Umbilicaria that grow on rocks. It can be found throughout northern parts of North America such as New England and the Rocky Mountains. It is edible when properly prepared and has been used as a food source in extreme cases when other food sources were unavailable, such as by early American northern explorers.
Umbilicaria esculenta is commonly used as a food in Asian cuisine and a restorative medicine in traditional Chinese medicine. It is called shi'er (石耳 "rock ear") in Chinese cuisine, iwatake (岩茸 "rock mushroom") in Japanese cuisine, and seogi (석이버섯) in Korean cuisine.
Rock Tripe(seogi) with pine nuts