Is an 18-metre prehistoric shark named Megalodon still out there? Sightings of massive sharks around the world suggest to some that it's possible. Is an 18-metre prehistoric shark named Megalodon still out there? Sightings of massive sharks around the world suggest to some that it's possible. Is an 18-metre prehistoric shark named Megalodon still out there? Sightings of massive sharks around the world suggest to some that it's possible. Is an 18-metre prehistoric shark named Megalodon still out there? Sightings of massive sharks around the world suggest to some that it's possible.