This is a citrus fruit, from the Rutaceae family, originating from the Sunda archipelago in the Molucca Sea. The tree and its fruit have the same name. It was introduced in the Indian ocean and Mauritius, by Pierre Poivre at the end of the eighteenth century.
You can use the zest for your broths and soups, stews, marinades and infusions. It works wonders in the water used to cook rice.