Zoas are an aquatic shellfish sandpit dwelling creature that lives in Maridia. They basically have the same mechanics as other pipe dwelling insectioid based creatures only difference is they come out of sand rather than man made air hole type structures. They come out out 5 at a time much like the Red Norfair pipe bugs and are very good for "grinding" off of which means picking up the missle and health upgrades they drop when killed.
Zoas are exclusive to Super Metroid and have yet to make another appearance.
 Super Metroid
Zoas are only found in some parts of Maridia and are the rarest of the "pipe dwelling" creatures only appearing in a few rooms of the game. They come out of the sand they presumably have nests in and charge directly at Samus. They respawn an infinite amount of times out of the sand and generally only used for grinding.
As they are a native to planet Zebes, it's possible their species go extinct after the destruction of the planet.