Now this is a bit more interesting:
Uranus was knocked on its side by a massive collsion, and I would not be surprised if these rocks were the result. Being in unstable orbits means that they may be removed if you can get a large enough spacecraft out to it. They may just be diamond rich. A diamond asteroid in a horseshoe orbit just needs a little more delta vee and off it goes.
I wonder if some of Neptune's new moons are ripe for harvesting as well.
I guess the can be called ice giants for a different reason too, now.