If sharks had dentists, one might want to set up shop at Muirfield Seamount, near a set of islands in the Indian Ocean. A recent expedition there pulled up a haul of more than 750 shark teeth—the largest ever seen at a single site. Most of the teeth came from modern-day species. But a few belonged to the ancestors of megalodon, which died out millions of years ago.

Scientists from Australia were conducting a research cruise in Cocos (Keeling) Islands Marine Park, around a collection of a couple of dozen islands. The Australian park is about 1700 miles off the country’s western coast.

The main purpose of the cruise was to evaluate life in the poorly studied waters. At the end of the cruise, researchers trawled the ocean floor, about three and a half miles deep. Their nets pulled up many species of life—including some that probably had never been seen before.

The haul also included the shark teeth. They ranged from about a third of an inch to four inches long. Most of them belonged to modern species—mako and relatives of the great white. But the biggest came from the ancestor of megalodon—the largest shark that ever lived. That means those teeth had been on the ocean floor for millions of years.

The scientists aren’t sure why this is such a popular spot for the teeth. Perhaps the contours of the ocean floor funneled the teeth to that spot. Or maybe it has been a gathering area for sharks—making it a graveyard for these ocean giants.