Arthur Jones, the older brother of UFC legend Jon Jones and a former NFL defensive lineman, has passed away at the age of 39. The news was confirmed on Friday morning, with no public details regarding the cause of death.Arthur was a Super Bowl champion with the Baltimore Ravens in 2013. He enjoyed a steady career in the league, also representing the Indianapolis Colts and Washington Redskins before retiring.Jon has credited Arthur and his younger brother, Chandler, for instilling confidence in him as a young kid to start training in martial arts. Arthur remained a steady presence at Jon’s fights, watching from ringside and standing firmly in his brother’s corner.The UFC extended its condolences through an official post on Instagram. Conor McGregor took to X to react to Arthur's demise, writing:"Very sad to hear this news, Arthur was a great man, a friendly giant! God, Arthur Jones."Check out Conor McGregor's X post below:Meanwhile, UFC color commentator Jon Anik wrote:"This is profoundly sad. As you can see from the outpouring of love, Arthur touched so many lives in our UFC community with his warmth and that smile. My heart is heavy for Jon and the entire Jones family."Former UFC lightweight contender Josh Thomson wrote:"Truly sad to see someone’s life gone so soon. Our sincere condolences to you, Jon Jones and the entire Jones family."Former UFC middleweight contender Derek Brunson also dropped a heartfelt message on X:"RIP, such a good dude. We connected years ago in ABQ, when he came to visit Jon. We chatted occasionally throughout the years. Blessings to the family. Gone too young!"Check out some of the reactions below:MMA world reacts to the death of Arthur Jones. [Screenshots courtesy: @ufc on Instagram and fighter accounts on X]When Arthur Jones spoke about watching his brother Jon fightArthur Jones claimed in the past that watching his younger brother Jon compete inside the octagon left him far more nervous than any NFL game he ever played.Despite being a Super Bowl champion used to high-pressure moments, Arthur said nothing compared to the helplessness of seeing his brother fight with no control over the outcome. He recalled how their mother instilled a deep sense of unity among the Jones brothers. Speaking in an interview with TMZ Sports, Arthur said:“I mean, I get more nervous than that. I can play football games all day. I can do it in my sleep, but when my brother’s out there in the octagon, man, I get the worst bubble guts, sweats. I’m a nervous wreck. He’s been successful for a long time, but I can’t control what happens when that cage locks. Me, being an older brother, you know, my mom always taught us one [of us] fights, we all fight. So we jumped a lot of people growing up, me, and my brother."