Esmeralda's Crystal Ball is an online magic trick that became a viral phenomenon. The trick consists of an interactive Flash file that asks the computer user to think of a symbol, which then mysteriously appears in a crystal ball on the computer screen. The trick is based on a fairly simple mathematical formula, but it fooled so many computer users into believing that their computer had supernatural powers, that Snopes dedicated a page to debunking the trick. The trick was later copied by various other Flash programmers who attempted to replicate the viral success of the original.