These are a type of fungus living off deteriorated tree trunks of various broad-leaved trees only forming semi-spherical caps.  

Ganoderma Mushrooms are newly recognized as the physical strengthener or sedatives for adult diseases such as insomnia, high blood pressure, diabetes, low blood pressure, arteriosclerosis and cancers.  Today, they are mostly artificially cultivated for better production.

Ganoderma is also called Maegisaeng or Jannabigeolsang.  In Eastern medicine, they were used for heart diseases or fevers but as recent findings revealed their carcinostatis substances, they are widely used for cancers.  

Originally, Maegisaeng referred to those living off of dead Japanese apricot trees but today they are not particularly separated from other species.  The taste is sweet and character is plain.  They enhance the vitality of heart, spleen, lung and liver and strengthen the muscles and bones.