The Metals Company sits on an untapped treasure trove of battery metals. But has the stock's ship already left the harbor?Investors who bought The Metals Company (TMC +4.54%) stock last December and held on through all the ups and downs of 2025 are now sitting on a gain of roughly 766%. Indeed, in mid-October, the company's stock had grown almost 11-fold year over year.Let that sink in. Literally: This might be the only company that grew exponentially on the promise of diving for polymetallic rocks about 18 ...