There’s more than one “unicorn’’ in the Knicks’ locker room this season. Kristaps Porzingis was dubbed a unicorn last season by Kevin Durant, but Derrick Rose has brought a second one with him.

It’s Rose’s trusty medicine ball, which he carries everywhere and nearly lost — twice — when he was in Chicago last Friday. Rose, who has had the ball since the 2010-2011 season with the Bulls, said the heavy ball is a perfect weight, which he has been unable to find anywhere else.

“It’s the only ball that’s like this in the U.S.,’’ Rose said. “It’s a 4.5-pound ball. Every other ball is three or six. No one else can find it. I’ve got a unicorn right here.’’

And he almost didn’t have it after his ballyhooed return to Chicago. Rose thought the Bulls staff had played a practical joke on him. The trusty ball, which helps with his shooting, originally was a gift from former Bulls assistant coach Ron Adams. He uses it in shooting drills to strengthen his leg muscles and as a result, he feels less body strain on his in-game jump shots.

“I lost it for 10, 15 minutes,’’ Rose said. “They couldn’t find it at the end of the game, then they brought it to me. Thank God. For sure I thought the Bulls stole it back.’’

As he left the United Center’s visitor’s locker room that night, however, Rose forgot the ball again. It was lying by his locker before a reporter called him back to retrieve it.

“People on my team know not to mess with it,’’ Rose said. “They know I travel with it everywhere along with my pillow.’’