The conch and the disk are symbols for alarm and destruction in the case of a danger such as evil thoughts or disease. Through the practice of yoga, one learns to recognize and eliminate these evil thoughts or diseases and reach God.
The Cobra has many symbols, every religion had some sort of serpent worship. In the ‘Hathayoga Paradipika’ the Lord of Serpents, Ananta (=infinite, eternal), supports the earth and protects it. It is believed that snakes shed their skins and emerge as new, therefore they are a symbol of eternity, fertility, regeneration, evolution and wisdom. It’s venom is poisonous but medicinal, it represents the practice of Yoga in which we learn how to convert emotions like anger, greed and lust to control, contentment, love and compassion.
The Human Torso symbolises the essence of Yoga, our evolution through the yoga practice. As Patanjali transformed from a small snake into a human body, so does anyone can grow, expand their intelligence and transform.