Symmetrical brain coral on a reef in the Caribbean Sea near Grand Cayman, Cayman Islands

This is your brain on puzzles. Brain coral

By using a long exposure and rotating the camera, a photographer highlights the spherical shape and grooved surface of a brain coral. You needn't be a genius to guess how brain coral got its name. But you could just as easily call it 'maze coral' after its labyrinthine surface. Either way, this sea organism is an apt mascot for today's cerebral celebration: Puzzle Day!

From mazes to math problems to minute mysteries, you can find puzzles to tease just about every part of your brain, from the logical left hemisphere to the creative and crafty right. While medical science hasn't fully established that regular practice with puzzles benefits the brain, it's thought that solving puzzles helps concentration, pattern recognition, and memory. Or maybe they're just fun—but hey, that's excuse enough to riddle away the day on your favorite puzzles. Try starting off with today's homepage quiz.