石耳一名石壁花，是地衣门石耳科植物。多生长于岩石之上，岩壁需湿润，体扁平，呈不规则圆形，像人耳一般。

石耳含多种维生素，营养价值极高。中国食用石耳的历史很早，《吕氏春秋》：“果之美者……汉上石耳。”吴瑞称:“石耳生天台、四明、河南宣州、萤山、巴西边缴诸山石崖上”"。李时珍《本草》亦云:"“庐山亦多，状如地耳，山僧采曝馈远，洗去沙土，作茹，胜于木耳，佳品也”。

石耳一年长不到几公分，要长得很大的话需要不少的时间，故又被称为百年蘑菇；再加上采集困难之缘故，其价格居高不下。

Umbilicaria esculenta is a lichen of the genus Umbilicaria that grows on rocks. It can be found in East Asia including in China, Japan, and Korea. It is edible when properly prepared and has been used as a food source and medicine. It is called iwatake (kanji: 岩茸 or 石茸) in Japanese and seogi (hangul: 석이; hanja: 石耳; literally "stone ear" or "rock ear") in Korean. The species name is based on the earlier basionym Gyrophora esculenta.