You can see the new organ illustrated below:

And while that doesn't change the structure that's been inside our bodies all along, with the reclassification comes a whole new field of medical science that could improve our health outcomes. "In the paper, which has been peer reviewed and assessed, we are now saying we have an organ in the body which hasn’t been acknowledged as such to date," said J Calvin Coffey, a researcher from the University Hospital Limerick in Ireland, who first discovered that the mesentery was an organ. Determining this is the next step for scientists, now that the organ’s anatomy and structure have been determined. Based on his findings, outlined in a paper published in November in The Lancet Gstroenterology & Hepatology, Coffey argues that “mesenteric science” should be its own specialized field of medical study. However, it was thought to be a fragmented structure consisting of separate parts until Dr. J. Calvin Coffey, a professor of surgery at the University of Limerick in Ireland, found evidence that it was one continuous organ. The anatomic description that had been laid down over 100 years of anatomy was incorrect.”

“The anatomic description that had been laid down over 100 years of anatomy was incorrect.” - Dr. J. Calvin Coffey

“This organ is far from fragmented and complex,” he added. Also Read: Being more social this New Year could help improve health

"Up till then it was regarded as fragmented, present here, absent elsewhere and a very complex structure. That means that medical students and researchers will now investigate what role - if any - the mesentery might play on abdominal diseases, and that understanding will hopefully lead to better outcomes for patients. More specifically, the organ is a double fold of connective tissue arising from the peritoneum ― the membrane lining the abdominal cavity ― that attaches the stomach, small intestine, pancreas, spleen and other organs to the posterior abdominal wall.
Scientists classify the mesentery as an organ, making it the 79th human organ. It connects the intestines to the abdominal cavity.