You see that blue block with a little dot in it? That's a naturally occurring Chance Cube. Chance Cubes look like giant dice, and they're one of the more unique (and more dangerous) features of my Minecraft world. Breaking a Chance Cube activates it, which will cause a random event to happen. These random events can range from a few item drops to drastic curses and monster spawns, so it's wise to be ready for anything before you get out your pickaxe.
If you're the gambling type, they can be made on demand. As the blue tint implies, they are made out of lapis lazuli, and nothing else. For now, it's not worth attempting to do that, but I might craft a few if there's ever a time where I don't mind being killed by magic, having my inventory wiped clean, or getting hit in the head by several anvils -- all of which are real possible outcomes of breaking a Chance Cube.