The true Lakshmi Shank is a rare sinistral Turbinella conch shell from the Indian Ocean, usually from Turbinella pyrum.
. One common substitution is the lightning whelk (Sinistrofulgur perversum, previously named Busycon perversum) from the Atlantic coast of North America.
The best authenticity test is to take an X-ray image of the Valampuri. In South India, people trust only the Rameshwaram type of Valampuries, and do not trust other varieties from West Coast and Bay of Bengal, though these are also the true Valampuries.
In South India, people specifically worship ‘Gauri Valampuri’. This Valampuri shows presence of small dark spots on its body whorl, near the conch cavity.