i agree with seeshell. i already thought of the wyrae as a sludge creatu :/ unless your talking about a creatu that stays as sludge which would be slightly different then the wyrae.
My immediate thought was of the Wyrae, which stays sludge-like for two of it's stages. I don't really see the need for another one. I kinda feel like that would take away from the Wyrae's individuality.