It goes without saying that many people fear what they can’t see. A murky lake that gives no signs as to what swims beneath its surface can be terrifying to those within it, an ominous cave which hides its occupant within the far back under the cover of darkness can make one who approaches it turn and run in fear, and a dense forest at night can make a lone camper feel like a scared child when the sounds of its hidden residents echo out from all around. The unseen is a major fear maker.