You've seen it at the Exploratorium, outside the bathrooms near our cafT: an amazing arrangement of tiles that form an optical illusion. The tiles appear to be crooked, but they're not! Now you can take this incredible illusion home with you in the form of lovely blue, white, and gray-colored, hand-painted, six-inch-square ceramic tile, which you can use as a trivet. Entertain your guests by using it on your holiday table - or, better yet, buy a bunch and build your own illusion wall at home!