A few years ago, I purchased a lump of glass from an estate sale for no other reason that it was beautiful and I wanted it. I set it on a shelf with the rest of my collectibles to collect dust. This morning at 8AM on the dot, the lump of glass shattered into a million pieces with a pretty loud explosion. There were no visible forces acting on it. No sunshine or anything else I could detect. I would love some theories about why this might have happened. Very curious.