The Ultimate Pizza Quiz

The iris is a part of the eye found in most mammals and birds. The iris works as the eye's aperture, which is similar to a camera’s own aperture! It does this by adjusting the size of the pupil to make sure the correct amount of light reaches the retina.

Einstein was an exceptional human being – and his brain was out of the ordinary, too! A study found that his parietal lobe was 15% larger than average. That’s the region of the brain that is responsible for mathematical thought and spatial cognition.

Jellyfish can sting with their tentacles if they brush against you when you're swimming in the ocean. You also can get stung if you step on a jellyfish, even a dead one. Usually, jellyfish stings will hurt, but are not emergencies.