Most construction management games have two types of currency. Animal Voyage: Island Adventure, however, has three types of currency. Coins and leaves are the primary currency. Coins are mainly used to buy new houses for your animals, while leaves are mostly used to expand into new territory. Crystals are the premium currency in Animal Voyage: Island Adventure. Their most important function is to buy new animals and speed up any task that you’re working on, but there are premium decorations that you can purchase using crystals as well.