Metal-eating spore

Metal-eating spores are fungus that can devour metal in extremely little time. It was developed by Cobra-La to use against Unicron.

Fiction

G.I. Joe vs. the Transformers

160,000 years ago, Cobra-La, the undisputed masters of biotechnology, needed only a moment's notice to develop a fungus capable of devouring metal when the Chaos Bringer arrived to consume their homeworld. Effectively threatening him with it, Cobra-La made a deal with the metal god to sacrifice the human race to him when they had become numerous enough to be a sufficient meal. Black Horizon, Part 1 of 2

The Yeti in service of Cobra-La continued the cultivation of the spores in wait for Unicron, in case matters would not unfold as agreed. When a counterforce was launched against Cobra-La, Flint and Joe Colton made their way to the spore farm, where they fought the Yeti for the only weapon against Unicron available. Cosmos came to their rescue. Though Joe at first warned him to stay at a distance because of the danger the spores posed to him, it was soon enough decided Cosmos was the only one both suited and present to bring the spores to where they would be useful: inside Unicron's head. Flint went along with the Mini Vehicle in order to keep him safe. After the expected obstacles, Flint used his one chance well to get the spores all over Unicron's brain.

Or as he put it:

Looks like we did some real damage. It'll be a while before Unicron terrorizes anyone with a brain full of this many holes. Ooh! There go those motor skills. And those memories from summercamp! Oh! And I doubt he'll be playing the piano anytime soon.{{#if:|{{{quote2}}}}}{{#if:|{{{2}}}{{#if:|, {{{3}}}|}}|}}

Black Horizon, Part 2 of 2