Cellulose nitrate was used to make dice from the late 1860s until the middle of the twentieth century, and the material remains stable for decades. Then, in a flash, they can dramatically decompose. Nitric acid is released in a process called outgassing. The dice cleave, crumble, and then implode.
From Dice: Deception, Fate & Rotten Luck by Ricky Jay and Rosamond Purcell, 2002.
Some casino dice in circulation are still made of this shit, and once you have one go acid it can infect all the dice it’s touching, and that’s why I’m distrustful bordering on terrified of casino dice