Butt Marker? Flat Bastard File? 9 Weird Home Tools and What They're Used For Butt Marker? Flat Bastard File? 9 Weird Home Tools and What They're Used For You may know a Phillips head screwdriver from a flathead, but do you know what a double cat's paw wrecking bar is used for? Test your tool IQ here! Margaret Heidenry, provided by FacebookTwitterEmail There are a few key factors that set us humans apart from the other mammals out there: self-awareness, language, and empathy among them. But according to Live Science, "The way humans make and use tools is perhaps what sets our species apart more than anything else."