Counch (sankha) is mainly available in two forms. The most common form is which opens in the left and the rarest form is that opens in the right hand side.
While pouring water to Surya or to the Linga the opening should be in the right hand side. It is believed that Lord Vishnu and Goddess Laxmi lives in this shankha as it is the most favourites of them. Worship of Lord Shiva also be done by this.
It is believed that its size grows bigger and bigger and the worshiper (user) of the daksinavarti sankh gets richer and achives all wordly comforts and development. Helps in incresing of prosperity, fame, happiness and wealth. It should be white/creamy in colour. There should be no black tinge, cracks or damages in it.
Generally damaged shankhas are sold in markets which are known as Dosha-Rahit, and gives negative results. Dosha-rahit shankhas are believed to destroy wealth and happiness.