SF Chowhound looking for a decent seafood restaurant with a main emphasis on raw oysters and raw littlenecks, but would also welcome a place that has more unusual selections as well (langoustines, whole sea urchin, cockles etc.). We're NOT looking for a white tablecloth place, unless the selection of exotic shellfish warrants the splurge. Right now I'm looking at Pearl's, Mary's, or Aquagrill (which seems to have more choices for shellfish if the online menus are correct?), but would certainly welcome any other choices. Thanks much!