After being Omicron Rho for some time and watching this on the internet (not mentioning my own research regarding the strangest planets), it is possible for law of physics to have something like a Gas Dwarfs or some other pretty-absurd-but-possible stellar bodies?
I remember there was a report about the Earth-like planet with size of Uranus, so...
I mean, I am pretty surprised by the fact there is a pure diamond planet or a huge iceball that is, actually, on fire all the time (and the planet does not melt).
Yes, there is theoretical Gas dwraf class. If you are curious, grab orbiter and 5631 stellar system modification for it - I have implemented such a planet there (Thick hydrogen atmosphere and solid rocky core http://www.orbiter-forum.com/showthread.php?t=33558)
