Its central core glows with the seven colors of the rainbow. Some people value the core as a gem.
– Pokemon Red/Blue Pokedex
Starmie is one of Misty’s signature Pokemon. When I played FireRed, I lost to her Starmie at first with my Charmander, because her Starmie was faster, forcing me to go back and grind until Charmander out-leveled it and was able to out-speed it. Its species name is the Mysterious Pokemon. It’s one of the few Pokemon without a distinct face or eyes (though I guess you can argue that the red gem in the center is its eye)
Starmie is known for being fast and able to learn many good attacking moves that have good combined coverage, like Ice Beam and Thunderbolt, as well as Psychic and Surf/Hydro pump. It’s a bit of a glass cannon though, having mediocre defense, and 5 weaknesses, but it can learn Recover to heal HP. It is one of the few Pokemon that started in Gen I in the Overused tier, and stayed there throughout into Gen V.