Is there an internet rule, where...

"If it exists, there will be an anime adaptation of it." ?

Serious question.

 Spoiler

Whilst reading and subsequently following a link from the Coraline TVTropes page, I read the page there "Beyond the Impossible," which showed the Schwerer Gustav. After looking this behemoth up on Google Images, I found that image up there...

I know theres rule 34, but is there something like that, but minus the porn aspect? Seeing that makes me believe...

Well, there is a rule that if it exists there's Touhou fanart of it, that's the closest one I can think of from the top of my head.