prov356 wrote: Links to documented occurrences, please. Until then, never heard of it.
That's like saying if it isn't on the internet it never happend , and that everything on the internet is true because.... well... it's on the internet!
I take everything including some stuff I get from here with a grain of salt. Every circumstance with living creatures (fish) can vary, as well as somebodies aquarium. Just as with any other product that is manufactured, not all are created equal. Defects happen even in the glass manufacturing business, and by viewing some of the articles that are in the library, who's to say an aquarium somebody has purchased isn't one that was made at home by another person possibly without a tempered bottom.
I have a 40-50lb rock that is going in my next tank and has some very rough points that jut out. Removing this from the previous tank when breaking it down while it was wet was a task in itself, all the substrate had been moved away underneath it from the Mbunas. I would rather trust the few dollar piece of plastic that was underneath it than chance breaking the glass from it slipping and causing what water was left to spill out damaging other stuff. Call me scared of what might happen by dropping a rock in my aquarium... sure I'll take that tag gladly.