The world’s largest natural pearl has been unveiled in the Philippines after a local fisherman says he kept it under his bed for ten years.

It has yet to be formally appraised by gemologists, but some are speculating that it could be worth millions. The giant pearl isn’t round like the “gem-quality” pearls usually used in jewelry. But measuring in at 2.2 feet (61 cm) by 1 foot (30cm) and weighing 34kg (75 lb), it appears to be the largest pearl ever found.

The unnamed fisherman told authorities he found the pearl a decade ago while freeing his ship’s anchor off the coast of Palawan Island in the Philippines. The man swam down to pull the anchor up, and in the process dislodged a giant clam that had been cultivating the pearl.

He kept the pearl at home as a good luck charm, he explained, until a fire this year forced him to move house, so he brought it to his aunt, a local tourism officer. The pearl is now on public display at the New Green City Hall in Puerto Princesa.

Pearls are actually a form of self-defense for mollusks with a shell, such as clams, oysters, mussels, and scallops. Scientists think that they form in response to a parasite or other invasive organism disturbing the mantle of the mollusk. The creature then releases a compound called nacre—mother of pearl—made of calcium carbonate and protein, that coats the invader. Lightweight but stronger than concrete, this substance builds up over years (even artificially cultured jewelry pearls require around three years). Giant clams can live for over 100 years and grow to be around four feet (1.2 m) and weigh over 227 kg (500 lb), potentially cultivating some pretty big pearls.

That said, natural pearls are extremely rare—according to National Geographic, pearls of value are found in less than one in 10,0000 wild pearl oysters. The previous largest known natural pearl was the Pearl of Lao Tzu, also known as the Pearl of Allah, weighing 6.4 kg (14 lb), measuring 9 inches (24 cm) in diameter, and valued at an estimated $35 million.

The newly discovered pearl’s value has yet to be determined by experts. Robert James of the International School of Gemology told Inverse that, in his opinion, it was unlikely the pearl would fetch the wild prices touted by some ($100 million is the number being thrown about). This blob-shaped pearl, he said, is more porcelain-like than gem-quality (flawless in shape, surface, color and luster).

Still, he expressed awe at the pearl as a product of time and nature. “This pearl could have started growing in this clam when the Titanic sank, for all we know,” he said.