All animals must eat to survive. If you've heard the term "grazer" before, it may bring to mind familiar farm animals, such as cows or sheep munching on pastureland. But the ocean has its own suite of grazers.
What killed the sultan Saladin, who famously unified the Muslim world during the 12th century, recaptured Jerusalem from the Christians and helped spark the Third Crusade? Until now, it was a mystery.