Obsidian Items are fire-proof!
Obsidian tools, few items, and a sword can be thrown into fire and lava and will not burn.
Obsidian+ Creative Tab (Before version 1.1.0)
Upgrading a Diamond Pickaxe on the Smithing Table
Smelting Obsidian into Scrap
Comparing Obsidian Blocks with Netherite Blocks.
These blocks literally have the same hardness as each other.
Swimming in Lava
You can swim in lava with Obsidian armor if you have a full set.
Beacon!
You can use these Blocks of Obsidian to construct a beacon. Can you craft a full pyramid using only Blocks of Obsidian?