Tonra was a purple tailed merman. He was the only merman Jack Sparrow had met during his teenage adventures. Tonra led young Jack to a room, which walls and ceiling were lined with hundreds of recesses, each holding crystal of different color that represented each of the sub-species of merfolk. They were crystals that controlled the merfolks' freedom as they were subjected to the power of the Trident of Poseidon. Later, Jack ended up destroying all the crystals except for the blue one.