"Restore party HP with the live-giving seas." - Coral's description in Dark Dawn.
When set, Coral increases base HP by 8, base Psynergy Points by 4, and base Defense by 2. When used, Coral will restore 50% of all allies' maximum HP.
Coral is located in Port Rago, in the interior portion called Port Rago Canal. Once Briggs arrives at the closed-off Port Rago docks building, and you climb into and go through Port Rago Canal to get inside the docks, use Grip on the movable set of stairs to reach the ground level above the ship. To the right of the ship is a bowl of water; cast Arid Heat on it to evaporate the water. A new opened black doorway should appear nearby; go through that doorway and collect Coral in the corner. Since Coral is located in Port Rago, it can be permanently missed once the final gate at the bottom of Belinsk Ruins is passed through later in the game.