What does an elver become when its grown up?

An elver is a juvenile European eel, and as it matures, it eventually becomes a fully grown eel. Adult eels are known for their elongated bodies and can live for many years, often migrating long distances between freshwater rivers and the Sargasso Sea to spawn. Once they reach adulthood, they undergo physical changes, including a shift from the transparent elver stage to a darker, more robust coloration.