A shadowy shape is visible in the distance, just under the surface of the ocean. The shadow swims closer, revealing itself to be a shark—an incredibly massive shark. Weighing as much as 30 large great white sharks, the megalodon is one frightening-looking fish. Luckily, it went extinct some 2.5 million years ago, so you don’t have to worry about seeing one today!

Supersize Shark

Since sharks first appeared hundreds of millions of years ago, the world has experienced ice ages, meteors, earthquakes, growing and shrinking seas, and more. Throughout all of these environmental changes, sharks have roamed the ocean.

The most famous prehistoric shark, Carcharocles megalodon, nicknamed megalodon or megatooth, ruled the seas from about 17 million years ago up to almost three million years ago. The colossal predator reached lengths up to 60 feet, stretching as long as a boxcar. The only marine animal ever to outweigh the massive megalodon is the blue whale, which weighs up to 200 tons, or just more than double the size of a megalodon.

Paleontologists estimate the humongous shark needed to devour 2,500 pounds of food a day. That’s like you having to eat 3,300 cans of tuna every day.

So. Many. Teeth

Like the rest of its body, megalodon’s mouth was huge, too. Its jaws could open wide enough to swallow two adults standing side by side. The giant shark used its sharp, banana-size teeth to chow down on whales, dolphins, seals, and probably other sharks.

Because sharks are constantly shedding their teeth—they lose thousands of choppers over a lifetime—and because megalodons were found in warm waters across Earth, their teeth have been discovered all over the world. Scientists have found hundreds of megalodon teeth in oceans and beaches in multiple countries. Studying them has helped researchers learn more about these extinct animals, like the fact that megalodons likely spent most of their time in shallow waters close to shore.

Being the biggest, toothiest fish in the sea didn’t always protect megalodons from predators, though. Newborn megalodons, which were only about six feet long, were likely sometimes eaten by other adult sharks.

Gone (but not forgotten)

The megalodon is an example of a shark that couldn’t adapt to its changing environment. Unlike people, animals can’t always move to a new location or find a new food source when their habitat changes.

Megalodons were adapted to warmer waters and needed lots of enormous marine mammals to feed on. Paleontologists think that when the climate changed a couple of million years ago and other large marine mammals moved into colder waters, the megalodons were left behind without enough food to survive.

Some people argue that megalodons could still be swimming in unseen parts of the ocean. Although it’s true much of the ocean has yet to be explored, scientists note it’d be really difficult to miss a 50-foot-long, nearshore shark with a taste for whales. Sadly, the megalodon is long gone.