I am 31 yeras old, i thought that I knew my penis pretty well but, about 2 weeks ago i noticed what seems like a knot or hard spot inside the head of my penis. It is about the size of the tip of my finger, it is not not painful nor has it changed the look of my penis. I was wondering if this is part of the corpus spongiosum, and have just never noticed it or can it possibly be a disease or cancer. I have been married for the last 6 years, with no other sexual partners. Please help. Thanks