Owls don't have eyeballs

What they have instead are better described as eye tubes. Since they can't move these tubes back and forth, owls have developed incredible neck flexibility to be able to see the world around them. They can turn their heads a whopping 270 degrees, whereas humans can only manage about 180.

As a result, owls have a special blood vessel system in their heads to keep fresh blood circulating to the brain when a quick head turn cuts off circulation.