Mighty Metal Men or Sinister Starfish?

The mascots of the Justice League/Society were in a pickle, as they faced alien entities with aggressive appetites. Starro the Starfish Conqueror invaded Earth with the goal of enslaving its population by attaching its mind-control miniature starfish, and the vessel of the Metal Men of Jupiter-Two known as Metal-X simply wanted to continue to feed and grow to mammoth proportions by instinct only.  When Snapper Carr stumbled upon Starro and realized that lime was the necessary component to neutralizing Starro, and when Johnny Thunder realized he needed the aid of his Justice Society allies to destroy Metal-X, they called upon their fellow heroes. 

What is interesting to the method in which the Justice League and Justice Society used to defeat these similar gigantic alien threats. The Earth-One Green Lantern soaked Starro with lime lather while Earth-Two's Green Lantern poured acid on Metal-X.

Starro would return from seeming extinction to plague Earth a few more times in the years to come. This included a robotic replica of Starro developed by T.O. Morrow, similar to Metal-X. As for the actual counterpart of the real Starro on Earth-Two, that was Nyarl-Amen and his clones, which sought to conquer the surface world until repulsed by Doctor Fate. 

Ultimately, Starro migrated first to Earth-C to battle the Zoo Crew, and still later to Earth-S during the Crisis on Infinite Earths. Metal-X apparently never returned... although the man behind its appearance still remained for the Justice Society to face soon thereafter.