Sun-Thrivers

A species of pink telepathic energy-beings that exist within a giant crystal at the heart of Krypton's sun.

Billions of years old, the Sun-Thrivers are compelled by their biology to surround themselves with "a vast quantity of solar-spawned gases." Using their mind powers, the beings draw "raw elements from other stars" and ignite themselves, becoming the giant red star known as Rao. Faced with the consequent problem of maintaining their "internal gravity" and thus keeping their "gases bonded together," the Sun-Thrivers fling off a "cluster of controlled mass" that coalesces in orbit around the sun into a new planetm which the beings identify as Krypton.

Deprived of the gravitational balance provided by Krypton after that planet's destruction billions of years later, the sun is reduced to an Orange Dwarf star, again threatening the health of the Sun-Thrivers. Their one chance of survival is to track down enough of Krypton's original mass and reabsorb it. To this end, the Sun-Thrivers lure Superman into deep space and tell him of their plight, noting that the remaining ten percent of the required matter, "a huge chunk containing the ruins of a great Kryptonian city," is beyond their reach and guarded by a Cardiac Creature, a huge heart-like alien that "pumps life-sustaining energy from the Green K" that the asteroid has been transformed into. Combining forces, Superman and the Sun-Thrivers defeat the creature and the remaining chunk is reabsorbed and then spun out of the sun as another new planet, known as Krypton-Two.

The new Krypton gives the Sun-Thrivers a temporary respite from extinction but the planet is fated like its predecessor to eventually blow up, threatening the existence of it's sun (S No.255, Aug 1972: "The Sun of Superman!").