The Shri Yantra, Sri Yantra, or Shri Chakra is a form of mystical diagram used in the Shri Vidya school of Hinduism. Its called mother of all yantras. ( symbols )
It consists of nine interlocking triangles that surround a central point known as a bindu. It symbolizes the harmony that lies in the different aspects of the physical world.
The union of female & male ( shakti & shiva )