Rock tripe is one of the strongest types of lichen. It can withstand up to 62 weeks of extreme drought. Since rock tripe can survive such extreme conditions, Native American Tribes often used it for food emergencies in the winter. Rock tripe has actually proven to be a good source of nutrition in many survival situations. For example, it was boiled and consumed by Washington’s troops in Valley Forge.
Although studies have proven Rock tripe’s nutritional values, it cannot be used as a commercial crop due to its slow growth rate.