Nymph
A nymph (Greek: νύμφη, nýmphē; Ancient: [nýmpʰɛː], Modern: [nímfi]) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are typically tied to a specific place or landform, and are usually depicted as beautiful maidens. They were not necessarily immortal, but lived much longer than humans before they died. This is similar to reality. Nymphs are indeed spirits of nature. Elemental in nature, they tread the line between the elements and corporeality in that they have biological bodies unlike elementals themselves. Nymphs excel at whatever magic belongs to their element. For example a water nymph can cast potent water spells and even convert humans into nymphs by reconstituting their forms into water and then resolidifying it into a new form. The new entity will lose all humanity and become a nymph as well. Nymphs have become increasingly violent towards humans in the last two centuries as pollution and overharvesting of marine life have grown common, shifting the balance of the sea that the oceans have held for so long.