Is Presence Of Extra Rib Possible Which Is Rubbing An Organ?

Hi! I was wondering if it is possible to have an extra rib? I feel like one of my ribs on the left side is rubbing an organ. I have mild pressure right under the bottom of my rib cage and if I feel my ribs (for lack of a better word, the floating one that wraps around from the back it feels like I have 2 of them and that one of them points straight down and is hittin an organ? Is that possible?