Oum

Oums are found in Maridia on the planet Zebes. They are very annoying creatures, because the will endlessly roll olong the edge of pipes and block you off from going any further. Making it worse, they are invincible to all of Samus' equipment. One (and most likely the only) good thing about these creatures, is that they also cause zero damage when touched, making them harmless, but very annoying.