big GIANT sponges the sponges start a war with the lemon-people and it is sooooo acidic from all the lemon-juice being spilled that the ebtire of the solar system is neutralized. the lemon people, in a last ditch attempt to destry the sponges, launch the Big Lemon, a gun that fires kamikaze lemons at things which then squirt their own juice at the enemy, causing them to go "Owww!!!" however, the plan fails when the sponges just absorb the juice.
the sponges counter by nukeing all the lemon groves on theor home planet, lemon-5. when all is done, the remainging lemons are rounded up and blended until their bodies are a fine gooy liquid. the ubér-sponge, known as 'da sponge', soaks up the juice and absorbs the knowledge of the Ancient Citrus, a force so powerful that it leads the sponge to destroy spongeworld and go mad. the fit sends him into hibernation, and what is left of the sponges leave this galaxy forever and live somewhere more pourous