Siren's Tear

Source
The Siren's Tear is sold by the Ahlurglgr in Borean Tundra for 100 Winterfin Clam. It has a very small chance to be contained in Darkwater Clam and Giant Darkwater Clam. It can also be found within a Bag of Fishing Treasures (Dalaran), which are rewarded from the fishing dailies Marcia Chase offer in Dalaran.