A hole?

I’m thinking slowly I guess, so it took me awhile to realize that the hole in the shadow was just a reflection from the mirror

[summerfield]

but wasn't the mirror facing a tad upward? it's a conundrum!

[Maggiemae]

How odd! Don't think Ive ever noticed that!

[Ann H. LeFevre]

Not slowly at all- for a woman with such a vivid imagination you were just thinking of all the magical possibilities it could be.