I' m sure that your missing brick was eaten. I did battle for months with a groundhog, never knew what nasty ornery critters they are until he moved into the yard. He ate all my tomatoes, climbed the Pawpaw tree and ate all of those, dug under the woodshed and settled in, squirreled away many rat logs. Borrowed live trap and succeeded in trapping three possums on three different nights, so had to drive miles to free them,(stinky ol' things) and never did get the groundhog. He didn't move, I did.