Mermaid World is an iOS game similar to the animal breeding games, but here you have mermaids with different traits, and when combined they sing, luring a new mermaid to join you. The goal is to collect all mermaids and fill their desires, by matching mermaids who like each other. The realms where mermaids live, can be decorated. Each realm also has a treasure chest, to where mermaids drop coins once in a while. The coins can be used to make in-app purchases. There are also pearls, which is a rare currency in game, and can be bought with real money. The game can be connected to facebook, which allows you to visit your friends' worlds, and share pearls each day.