The Glowstone is a completely sealed rubber pebble of light with a strong metal spine. It's wireless recharge only, has no sockets and therefore no weak points on its body, making it inherently tough while still being wearable, small and lightweight.

It means you can put it in some pretty extreme conditions, like a boiling pan or a block of ice, and it keeps working. You can even throw it off a 4 story building and it still work. That's the benefit of having an IP69K waterproofed and ATEX rated product.