What is believed to be the world’s second-largest documented pearl is being auctioned by Bonhams Auction House on December 6. Valued between $300,000 and $400,000, the five-pound gem found off the coast of the Philippines is a human-brain-shaped-pearl and is accompanied by the lower half of its original giant clamshell. Dubbed the “Palawan Princess,” the gem is next to the 14-pound “Pearl of Allah” in size. Known for its reputation for holding auctions of items in various categories, the auction house is also putting up a diverse array of objects d’art, unusual gemstones, and gold, gold nuggets and native metals for auction.