If the photo is not visible, let me know, and I'll try another way to get it posted.
When cleaning both of the cow elk my dad and I harvested in Idaho in October, we noticed that they both had "stuff" along their spine. Mine was a younger cow, about three years old, and the growths were dense. Above image is from her just near the tenderloins. Dad's cow was really old and the growths were much less dense and smaller. Nothing in the meat of either cow, just in the body cavity running the full length from the neck to the tail. Myself, my father, and the ranch owner had never seen anything like it. Turns out the meat processor in Grangeville had never seen it either. I cut a few off and inspected them, finding them to be "organ" like rather than parasite like. Thought they might be some kind of tumor.
I finally put in 10 minutes of internet time and found the term "hemal nodes". Mini spleens. Found in most ungulates. And is thought to be genetic as not all critters will have them.
