Shockingly, the most oversized member of the Green Lanterns does have a ring of its own, but it might be a bit negligent with it. Hal Jordan discovered where Mogo keeps its ring and the odd use Mogo has for it.
The ranks of the Green Lantern Corps are filled with some of the most willful beings in the DC Universe. Aside from the handful of humans that have met the Corps high standards, the organization is composed of aliens from every corner of outer space. This, of course, means there are some surprising Green Lanterns, like a living math equation, or sentient germs. But one of the most notable members has got to be Mogo, a living planet. Not only does Mogo serve as a Green Lantern, it plays an important role in the Corps, using its telepathic powers to deliver Green Lantern Power Rings all across the DCU.
Despite Mogo's importance to the Corps, and the pride it takes in handing out Power Rings, the satellite Green Lantern seems to keep its own ring in a very curious place. In Green Lantern #28 by Robert Venditti and Billy Tan, things go sideways when Supergirl joins the Red Lantern Corps. The young hero menaces a couple of Lanterns who bring her to Mogo, who is serving as the new base for the Green Lanterns. The Corps' newest leader, Hal Jordan, is shocked at the sight of a Red Lantern/Kryptonian hybrid and recognizes that her Red Lantern abilities need to be neutralized immediately. Hal finds the Blue Lantern Saint Walker tending to Mogo's natural wildlife where Hal discovers Mogo has an average-sized ring, but it leaves it out for the squirrel-like treemunks to play with.
Jordan isn’t wrong thinking Mogo’s ring was at its core, as the “War of the Green Lanterns” arc revealed the Lantern has a giant one that serves as its 'brain'. But Mogo having a similar size ring to every other Corps member makes a lot more sense as Power Rings need to be able to be passed on to a Lantern’s successor. While it’s true that the planet doesn’t have fingers or tentacles or any sort of limb to affix its ring, leaving it out as a toy for animals could be a dangerous move for Mogo.
In this one moment alone, Mogo makes mention that it can’t keep track of its inhabitant no more than Green Lantern can place any specific bacteria on his skin. Meaning there could be forces on Mogo that it isn’t aware of, ones that could be seeking out a weapon as powerful as a Green Lantern’s ring. It's sweet that Mogo wants to entertain the creatures that live on its surface, but without any security measures in place, it could be offering up its ring on a silver platter to any villain that comes its way. Unless Mogo comes up with a good hiding spot for his ring, the Green Lantern is putting his own ring at serious risk.