The name of what the last poster was talking about is a lipoma. Normally, they say if you can squish it at all, then it's a lipoma (unless it's where a lymph node should be, then it's probably a lymph node). I don't think there are lymph nodes in the area you are describing, you might want to check out an anatomy book from a library or look at an online copy of Gray's Anatomy to be sure. I've got a lipoma behind my ear. They also say that if you have one lipoma, you will be prone to others. Also, there's a type of cyst you can get called a ganglion. My dad gets these on his wrist. They just puncture them to get rid of them, but they feel pretty hard while they're there, even though they're just fluid. Another possibility is a calcification, which sometimes your body gets confused and puts calcium in the wrong spot. It would probably be good for him to get it checked out, but usually if it's just one spot in isolation, the doctors don't worry about it too much, unless it's causing him pain or discomfort. There are things they can do to get rid of all of the conditions I listed, so if it bothers him at all, he might want to see if he can get it removed. Lipomas and ganglions are especially easy to get rid of.