Needlers are strange, spherical organisms covered in spikes or needles, giving them a superficial resemblance to land-based sea urchins. They seem to use these needles to puncture whatever they are mobilized upon, allowing them to essentially crawl along any surface available. They are normally docile, but these spikes are obviously dangerous as they are not only intended for movement but also for defense.
When the Biologic Space Laboratory Research Station took orbit above planet SR388, they were apparently uninterested in such a low-grade species, and left them on the surface (although it is equally possible that events unfolded before they had a chance to obtain Needler specimens). When the planet was apparently destroyed in the blast radius of the BSL, the Needlers went with it in a blaze of glorified extinction.
- Metroid II: Return of Samus (First appearance)