Micropolygons are what Poser (and all Reyes renderers) use to do polygon smoothing.  If it still isn't rendering with a smooth-looking surface there might be caused by depth-mapped shadows, which cause a variety of crappy artifacts - try rendering with shadows turned off and see if it looks any different.  It seems likely to me that it's just wonky phong shading coming from those long polygons that go from the outside of the saucer to the center, you might also check to see if those are broken from the inner "hub" structure".

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