We are discovering new types of planets constantly. Along with those mentioned, astronomers have discovered diamond planets (
http://www.ibtimes.com/discovery-dia...y-world-847633) and Hot Neptunes (
http://www.centauri-dreams.org/?p=1263).
Here is a real world list of planet types -
http://en.wikipedia.org/wiki/List_of_planet_types
Like the situation with dinosaurs - where certain types of species will never be discovered because of where they lived, that there may be planet types that we might never discover.
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http://blogs.smithsonianmag.com/dino...the-dinosaurs/