The phrase "immovable object" refers to something that cannot be moved or changed, no matter how much force or effort is exerted on it. Full definition
He'd been touched by scandal, but he'd also been described, more than once, as Teflon — a rare immovable object in Albany's raucous political climate, thorn in the side of governors and mayors who'd long since come and gone. (observer.com)
And here is one of those «irresistible force meet immovable object» moments in ecodesign. (treehugger.com)
Holding a club in various positions against immovable objects and straining the muscles employed at those points, he has lengthened his drives 15 yards. (si.com)