In 2017, you’d think doctors would know the human anatomy thoroughly, but researchers recently were surprised to discover a completely new body organ. The organ is called the mesentery, it resides in our digestive tract, and may hold the key to better understanding digestive disorders.

The mesentery didn't just appear from thin air. According to ScienceAlert, it was previously believed to be made of fragmented, separate structures. However, new research has shown that it's actually one continuous organ. The discovery that the mesentery is actually a continuous structure was actually made in 2012, but it has taken four years of further research before the findings could be officially released. Grey’s Anatomy, the world’s most famous medical textbooks, have even been edited to include the update.

Still, it’s unclear exactly what the mesentery does. The body part has been long ignored and believed to be otherwise useless, but scientists are beginning to change their ideas on its function.

“Now we have established anatomy and the structure. The next step is the function. If you understand the function you can identify abnormal function, and then you have disease, said J. Calvin Coffey, a researcher from the University Hospital Limerick in Ireland who helped to identify the organ, ScienceAlertreported. “Put them all together and you have the field of mesenteric science … the basis for a whole new area of science.”

While it may be hard to believe, this is not the first time that scientists have recently discovered a new body part. In 2015, scientists discovered a “missing link” between the immune system and the brain which they dubbed the "central nervous system lymphatic system vessels.” The team believes that the “missing link” between the brain and the immune system could explain why some diseases like Alzheimer’s can cause plaque buildup in the brain, and may offer insight into the pathology of other illnesses as well. More research is needed.