The very first enemies encountered and could be considered the “Goomba” of the Metroid series. One could imagine a Zoomer as a giant insect the size of a small dog, with foot-long spikes protruding from its back. The Zoomer is a very adaptable species in that they can live and climb almost anywhere, which is surprising despite their large size. Be careful where you tread - a Zoomer can follow you through an open hatch into the next room, harming you in the process. Yellow Zoomers are the weaker of the species while red ones take a little bit more to kill.
Anything in Samus's arsenal can destroy a Zoomer. However, they often crawl on the ground and so must be destroyed with Bombs or Screw Attack. Due to their weak nature, Zoomers are great for collecting Energy and Missile pickups. Be careful, though, as Zoomers can crawl just about anywhere, including pipes!
Due to some confusion over the Japanese katakana Gi (ジ) and Zu (ヅ), its Japanese name (prounounced “Jee-ma”) was mistranslated as “Zoomer” in the NA instruction manual. They were more closely translated as "Geemer" in Super Metroid, but were recalled Zoomer in Zero Mission. Retro Studios played on this idea for the Prime series, and put both names in the game, turning them into two different species.
If Samus shoots out a destroyable block while a Zoomer is crawling along its edge, the Zoomer will go into an infinite spinning loop in mid-air. Then it's just a matter of either laughing at its predicament, or putting it out of its misery.