Sri Meru Prastha Sampurna Sri Yantra The king of the yantra is Sri Yantra. When it is placed on the back of the tortoise then its strength and auspiciousness increases manifold. The tortoise is particularly relevant as it is a very powerful, protected being that can live in either water or land. It is also non-violent and Nature has provided it with a strong cover or jacket to protect it from danger. Tortoise is gifted with long life therefore in Vastu Shastra and in Feng Shui it is believed that its presence in home will give long life and health