Dakshinavarti Shankh, Valampuri Sanggu; or Sri Lakshmi Shankh, is a sacred Hindu object otherwise known in English as a conch shell. This is the shell of a large sea snail from the Indian Ocean (a shell of the species Turbinella pyrum), but one that has the very rare reverse-turning spiral.
In other words, when it is held with the spout (siphonal canal) pointed up, this conch’s spiral twists rightwards (dakshinavarti) rather than very much more common form, which twists leftwards (vamavarti).
Genuine Dakshinavarti Lakshmi Conches are only found in the Indian Ocean, between Myanmar (Burma) all the way to Sri Lanka. There are three main localities of this shankh in India. Shells from all the localities show definite morphological variations. The three localities are the Indian Ocean near Ram Setu, Sri Lanka, Ramishwaram to Tuticorin. Shells from this region are rare in occurrence. The second locality is Arabian Sea or Western India. The third locality is Bay of Bengal.
The Lakshmi Conch is said to bring all manner of blessing, but particularly material wealth, upon the owner. Ritual use may include bathing deities, drinking from the conch, or the use of mantras oriented to goddess Lakshmi. It is a wonderful object for Vastu purpose giving high positive energy.
Image source: http://www.sazmahal.com/shankh.html