Meg Murl, What Are You Doing?

Two jackal-headed human figures are painted so as to appear to be holding a real bronze chest that protrudes from the wall. The face has a huge O of a mouth, if you will. Inside of which the space is dead black. It's three feet in diameter. I throw chance lance into it. We did it, and then I call it back. Oh, no, you don't. Don't put your hands into the O face. Whatever you're about to do, you'll die.