User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-26074976-20130327135640/@comment-3195217-20130327142739

They're used for the Ancient armor. I don't know their name in the western versions, but in P3rd and in the Japanese 3G they are called Atea/Ancient. They consist of 3 pieces (torso, arms, legs) and have useful skill points in them for custom sets. Ancient X leggings for example gives +5 FreeElement if I recall correctly. so keep them. In P3rd it was a pain to farm them, 3U I have no idea about, because my copy still didn't arrive...