This is Ganoderma lucidum, basically it is a polypore fungi, , host tree- Quercus semicarpifolia (from Uttarkashi, India) causing root rot , having numerous medicinal properties, also called Rishi Mushroom
Ganoderma is a genus of polypore mushrooms that grow on wood, and include about 80 species, many from tropical regions. I am working on wood decay fungi.. sometime species is same but host are different then may be a chance of variation in color, shape and size