What Is This!?

I need your help. You guys are my last hope. Thought I never noticed until recently, I have always had what felt like a knot in my stomach, for as long as I could remember. It was several inches to the right of my belly button. One day, a few months ago, I was playing volleyball with some friends, and me and one of my teammates jumps up at the same time, and smacked into each other. While the impact was taken on my left side, I felt something strange on my right, where the knot was. From that point, for about 2 week, I have horrible abdominal pain, which just continued to get worse. Nothing made it better.

After going to the doctor, he found that there was something in my body, moving around freely. After Cat scans and X-rays and sonograms, and all that junk, they decided finally to take out whatever it is, and I went under the knife. When I woke up, I found out what my knot was:






My guess is that it was lodged in my Abdomen all these years, but I never noticed will it came lose, from what I am guessing is the impact during the volleyball game. And the tearing, as well as the lose object, it was caused my stomach ache.

NO BODY has any clue that this thing is. It is about 3.5 cm in circumference on the top I’ve shown in the picture, and about 5 cm long. I haven't told anyone about it, and my Doctor is being very discrete, as I have asked him. Does anyone know what this is? I know it is a long shot, But I'm at my wit's end, I figured I would ask you guys, on the off chance that you may have any theories.