This pearl was called Palawan Princess,Possibly the second largest pearl ever discovered and documented, surpassed only by the renowned 14 pound (approx 31,893.5 carats) “Pearl of Allah” (so-called because it resembled the turbaned head of Allah), the present pearl is the product of the giant clam shell Tridacna gigas found off the coastal waters of the Philippines. this pearl measuring 15.24 cm with an estimated price of GPP 250.000 or approximately $400.000.
The natural non-nacreous pearl was found in saltwater near the Philippines' Palawan island and "bears an uncanny resemblance to a human brain," the auction house said. Both rare and immense, the gem is thought to be surpassed in size only by the 14-pound "Pearl of Allah," an approximately 14-pound, 31,893.5-carat pearl that, like the Palawan Princess, was the product of the giant clam shell Tridacna gigas and was also found off the coastal waters of the Philippines.
The approximately 11,339-carat Palawan Princess is a blister pearl measuring six inches in diameter and accompanied by the lower half of its original giant clam shell, which shows the point of attachment where the pearl formed.
These pearls will be sold in an auction in Los Angeles next December 6. here is the picture of those World Second Biggest Pearls "Palawan Princess"