Essence of the Twin Seas

Essence of the Twin Seas was a Legendary Crafting Material in Diablo III. It required a Character Level of 1 to use, was account bound, and could be stacked up to 1000 times. It was required for the crafting of each piece of the Captain Crimson's Trimmings set. As of patch 2.0.6., it no longer drops, and existing Essences may be sold for 50,000 Gold.

The item had a chance to drop off the unique Sand Sharks:
 * Razormouth (Black Canyon Mines)
 * Monstrous Dune Thresher (Stinging Winds)
 * Moontooth Dreadshark (Sewers of Caldeum)

Strangely, sand sharks find this essence irresistible.