OK, I just came from the doctor TODAY where I was examined for the EXACT SAME PROBLEM. I gained a lot of weight from an illness, which I am now losing (down 65 pounds so far!). As I lose weight, the omentum (belly fat that now hangs down) has hung down more, so instead of my belly sticky out, it now sags down. About two months ago, I started noticing a hardened area at the bottom of my belly. It has been growing (the hardened parts), and that was examined at the doctor today.
It is fat that has "settled" or re-distributed to that location, and it IS HARDENED FAT -- everyone else commenting here that it's not, you are all mis-informed, sorry to say.
IMPORTANT: This hardened stomach fat can, according to my doctor, a) get infected, and/or b)develop into necrosis (dead tissue). Both of those conditions are VERY SERIOUS and require surgery to excise the infected/dead tissue.
WHAT TO DO: Massage the hardened area frequently, and not too hard (do not cause an abrasion on yourself!). Use body oil or lotion when massaging.. This moisturizes the skin and allows you to work the hardened area. Definitely go to the doctor and start monitoring it closely. It can turn ugly, but from the sounds of it you have caught it early enough.
If you keep massaging it, and if you are also dropping some weight, you can soften up the tissue enough that it doesn't get infected or necrotic. Then later, when you are nearer to your goal weight, you can get a tummy tuck if the omentum is still a problem.
Hope that helps, and best of luck with it -- I am starting my massaging tonight!!! xox
PS to the person who has discoloration around the hardened belly fat -- Please, please, get to a doctor IMMEDIATELY. Discoloration is a sign that there is a more serious problem.