Mahagauri is the kriya Shakti of existence . Kriya means action , the energy which creates motion in static matter is Mahagauri . She is the eighth manifestation of Goddess Durga who is worshiped on Maha Durgashtami . She is the beloved wife of Lord Shiva, who is meditated upon seated on Nandi, the bull. She has four hands in which she holds a trident , damru , abhaya and Vara mudras. She is saumyamukhi or has blissful expression on face .