The Lost Language of Dera

Dera is a settlement town that was founded about halfway between Treford and Frais well before the those two towns became the large places they are today. Out of all the ruins that are left, people today can see that the settlers didn't speak any humanoid dialects that are known today; instead, they "spoke" to each other with colors and hand gestures.
This was found out only because of the mers - one of the people from Dera became a pirate, and in time they were caught, sentenced, and thrown off of the ship at World's Scar & Cliff's to Land's Edge. They would have drowned at that point if the Heart Guard hadn't saved them and place them in the "bubble" of air at the bottom of the ocean floor. They spoke to others around them, but wasn't understood. One of the mer at that time coaxed the criminal to make a recording of their language - the man did the best he could with the colors that were allotted to him at underwater, and so there is a recording of another woman talking to him and saying what movements he was making with his fingers, hands, and even parts of his body.
Water = two hands crossing over each other, stopping when the movement hit the middle of the arm, and then "flowing back." Mer = take the pointer finger and the middle finger, curl the other fingers onto the palm of the hand, and flex them two times Coral pink = a person who enjoys using their body Clear air = unseen or ghost
The person eventually died, their name unknow, and the recording was lost amongst the treasures the mers kept when one of their new friends died. Finally, about fifty years ago, a mer chanced to see a recording shell amongst all the items and wanted to listen to it. She brought it to the attention of academics, who realized there was a whole language that had been lost to time. It's still being pieced back together, one fragment at a time.