Sova



Novas are strange heat-loving creatures that have fire on their backs. They move around slowly, and can only be defeated if first frozen then destroyed with missiles. The exeption to this is in Metroid fusion where they can be destroyed by simply a series of charge beams. In the Zebes-based Metroid games, they appear primarily in Norfair, and sometimes in Ridley's Lair.

Metroid Manual
"Their entire bodies are covered in spiky, fireproof wool and they crawl around the floor. A missile blast will kill them. If using the normal beam, it takes two blasts to kill the blue ones and four blasts to kill the yellow ones."