Molten Shard
The molten shard is a giant lava rock in The Legend of Zelda: Twilight Princess that falls out of Death Mountain thanks to Fyrus. Luckily enough, it never hits you. The shard is also used to melt all the ice away in Zora's Domain.
After the Molten Shard has been used to free the Zoras, and the Lanayru Province has been freed from the Twilight, the Shard can be blown open using a Water Bomb to reveal a trapped Goron (who apparently fell into the lava in Death Mountain and was blown violently out of the volcano while inside the rock). Once freed, the Goron will give you a Bomb Bag.