I happened to notice this clinging to my kitchen wall today. It is a piece of Rice Chex. But not just any ordinary cereal tibit. It was dried...more like petrified. And glued securely in place. Don't know how long it's been there, but I injured myself trying to scrape it off with a butterknife. My hand slipped and I cut my knuckle on one of it's sharp corners. Drew blood and everything. Then I tried putting a wet cloth on it to soak it off. I tried spraying it with a multi-purpose cleaner. It is still there.