Yamebas share the ability to hover through the air, and has the ability to increase its size whenever an X Parasite merges with it. These creatures slowly drain off energy from Samus whenever she is in direct contact with their outer membranes, similar to a Metroid larva. However, Samus can effortlessly walk away from their grip to avoid damage, causing the Yameba to give chase in an attempt re-attach itself to her; these traits are shared with Mochtroids.
- Despite their behavior, this creature is not a Metroid. However, Metroid Prime and Metroid Fusion: Prima's Official Strategy Guide erroneously refers to them as Metroids in one instance.
- It somewhat resembles a Meboid or Flitt in appearance, which would seem to suggest that the Yameba is an infected and/or X-mimicked version of one of the mentioned creatures. It is possible however, that this organism was an entirely new creature which Samus has never encountered before that was among the captured specimens of the Biologic Space Laboratories; this is supported by its unique Japanese name, which is not shared with any previous enemy in the series.
- In trailers for Fusion, their core nuclei are colored purple and their membranes are orange, rather than the green core and blue membrane seen in the final version of the game. They are also seen on the Main Deck, where they never were in-game.