I kinda have the grate thing too. I think mine stems from the movie "Hunchback of the Notre Dame" , (Ithink it was) where the monster was held captive in an underground grate covered thingy. Kinda like the movie with the doll cutting ankle straps from under the bed. And then there was that ad in the old comics about smallpox right next to the xray glasses and disapearing ink.
