This is not my picture but you get the idea. I was too upset to take any.
What happened was that the bath store I ordered the vanity set from didn't bond/glue the undermount sinks to the countertop. Instead, they screwed four brackets into the countertop to hold the sinks in place (who does that?!). The screws obviously weakened the already-thin marble slab. My contractors sensed something was off as they were transporting it from downstairs -- the sinks actually moved around and almost fell off! There is a huge gap between the sinks and the bottom of the countertop. How the heck were we supposed to use it on a daily basis, and still expect there'd be no water leaks? After they laid the countertop onto the vanity, our contractors did the right thing by deciding to take it off to glue the sinks. As they were lifting it, the tragedy happened.
The completion of our bathroom reno was delayed until Saturday thanks to this sudden death. C'est la vie!