I usually do 500 crunches a day but still don't get properly toned in the stomach area does this mean there's hardened fat or i just gotta work harder?

Over/underlying fat: Crunches just strengthen the central and upper portion of the stomach muscles. First need to look to see if you are exercising all of the components of your abdomen (obliques etc.). Problem often is there is fat being stored overlying the fat or under the abdominal muscles in the omentum of the intestines. This fat is the hardest to lose.