An original character by oso (toolate) that is a personification of the 'Gyromitra esculenta' species of mushroom, also known as the brain mushroom or elephant ear.
Her name is listed on oso's website and in his artbook as "Shaguma Esculenta," Shaguma being her given name (シャグマ・エスクレンタ.) This is based on the Japanese name of the mushroom, shaguma-amigasatake.