This week in space: Siberian and other cavern craters

So this mysterious Siberian Crater has people throwing out all kinds of theories... 

It reminds me of the one on Mars

It also reminds me of the one on the moon


Now, I have a really good theory on what has caused these... one I've not seen mentioned yet. You see my friends, I whole-heartedly believe these are caused by one thing. A terrible menace. GRABOIDS.