Well I actually have an idea of how it could have busted. My 29 gallon didn't always sit where it sits today. It used to be about 8 feet over. I switched the places with another tank a few months back. So one night, I moved one stand out of the way cuz it was on a computer desk and it could move real easy on my carpet. So I took out almost all of my water until there was maybe 3-5 gallons left from my 29 gallon then I started pushing on the stand and slowly I pushed it to where it now rests over the period of about 1-2 hours.
Also I'm not gonna lie, I have thrown things and they have hit the tank before. I'm 14, what can I say. But none of them hit the tank "too" hard. I think a pocket knife once hit it. And that was the worst of it, the rest of the things were like maybe marbles, pencils. That kind of things. Those 2 things probably are what made it crack .
I didn't say I throw things at my fish tank. I say that I throw things and they hit my fish tank occasionally. I just throw things up in the air and catch them. Most of the time I catch them, but sometimes they go flying and end up somewhere else.