Some people are just retarded.

Now, I'm no Islamic scholar or anything, but I'd think if someone wanted to secretly make something look like a mihrab, they'd make it look more like this:
Or like this:
And not like this:

I mean I'm just saying. A mihrab is supposed to represent a door, as in the gateway to Islam. That's why they tend to look like a door, and not like a crescent.

Read the comment thread over at this post at TBogg, and you'll understand. Some people are just retarded.