Carotid artery disease is caused by a buildup of plaques in arteries that deliver blood to your brain. Plaques are clumps of cholesterol, calcium, fibrous tissue and other cellular debris that gather at microscopic injury sites within the artery. This process is called atherosclerosis.
Great white sharks may not be the world's biggest sharks, since that title goes to the whale shark, but they are the planet's largest known predatory fish. Whale sharks and great whites couldn't be more different in temperament.
The megalodon shark (C. megalodon) is widely regarded as both the largest shark to have ever lived on Earth and one of the largest vertebrate predators in history. Megalodons roamed the seas from around 28 million years ago until ~1.6 million years ago, when they were wiped out during the Pleistocene extinction.