Staryu is a golden-brown, echinoderm Pokémon with five appendages. These appendages surround an exterior organ called the core. The core resembles a golden metal casing with a red gem in the center, which is held in place by a golden ring looped around Staryu's lower left point. If any of Staryu's appendages are lost or eaten by predators like Lumineon, it is unharmed and can grow them back with ease provided the core is still intact.

When the sun goes down, Staryu's core glows its brightest. Many Staryu will float from the seafloor to the surface and align themselves with stars of the night sky as their core flickers, displaying a connection with the celestial bodies of space. The anime has shown that if Staryu becomes weak, its core will grow faint and flash slowly. During the ends of summer, groups of Staryu tend to gather while lighting up in a steady rhythm. Staryu can be found at the very bottom of the ocean on the seafloors. There are times, however, when Staryu finds itself in rivers that lead into the ocean as seen in Pokémon Snap.

In the Pocket Monsters Encyclopedia, and the original Japanese version of the anime episode The Water Flowers of Cerulean City (EP007), Staryu is classified as hermaphroditic.

Evolution
Staryu evolves into .

(Source: Bulbapedia)