It escaped when it outgrew its silo.
Bullets danced from the stupendous shell, and RPGs left not a blemish.
The General ran after it - a sad figure he was, amid the devastation; in vain, he emptied his side arm after the colossus, before sinking to his knees, muttering:
"What have we done? What have we done?"
Heedless, the monster smashed through the perimeter fence - 50,000 volts sparking against its impervious, calcified flanks... And then, with regal poise and disdain, it lumbered toward the sanctuary of the nearest forest...
"General..!" I cried - "...We must call in an air-strike, before it can lay!!"
But the General had ceased to comprehend the meaning of events, or even the significance of his own name...
How many times had I pleaded with him - begged him - to dispose of that mollusc, before it dispensed with us?
Alas, no one listened...
"We have to inform the president" I said - more to myself than anyone else...
"No!" cried out the General as though stung. "We will handle this!"
And with that he leapt into action, proceeding directly to his bunker...
Now, the local National Guard commander was also a golfing partner, and so there was soon assembled an impressive task force - equipped with tanks, howitzers, rockets and the entire inventory of "Smithers' - Snail and Slug".
But it was hopeless; neither poison, nor artillery had any effect on the monster - which simply smothered its foes under a glistening trail of slime...
Only then was an air strike called in; but aerial rockets and cannon proved just as useless against the beast; again and again the fighter-bombers swooped and strafed - again and again - and with no effect what-so-ever. And then, in a moment of tragic inattention, one of the fighters was lost - smote, by a giant eye stalk.
Thus, the giant snail escaped again - seeking refuge among the mountains and valleys; the terrain that had kept our genetic weapons program so secret..
It trailed eggs by the thousand, it devoured meadows by the acre, and it snaffled trees as though they were pretzels.
As chief genetic designer, I knew all too well what would follow:
The myriad eggs would hatch into baby snails the size of basket balls; within an hour they would grow to the size of VWs; and, within just ten days, they would each attain a displacement greater than an aircraft carrier. The voracious hulks would then fan out in search of sustenance: crushing, smothering and chomping great swaths across the land - just as we'd designed them to... (to the enemy that is)
The President looked at me, dazed..
"A giant what?"
"A snail, Sir. It's a giant snail"
"I don't remember signing for that.. Did I sign for that?"
"Well, it's there Sir, and it does threaten civilization as we know it, Mr President, Sir"
"Uh-huh... Okay.. so then we'll just nuke it.."
"But.."
"Yup, we'll do that.. And, um, thanks for dropping by, professor..."
And before I could say more, I was hustled from the Oval Office, and into a conveniently parked police car.
So it was that a B-52, laden with nuclear weapons, was sent to reduce our creation to so much steaming escargot... And, in the dawn following the snail's last stand, all that remained was a giant, charred shell - towering against a reddened sky...
..And I must admit feeling a certain secret grief, and a hint of professional pride, for the marvel and mayhem that was our secret, giant snail.
Later, still in my cell, I learned that the shell had been transported to Malibu, where it was renovated and turned into a luxury condominium complex.
Currently, it houses 287 spacious apartments, a sports club and a casino - all of which I think is in rather poor taste...
But then, what would I know? I'm just a scientist...