Usurian

The Usurians are sea kale-like beings native to Usurius. They don't need to breath and look like green liquids in their natural form, though they can take the forms of humanoids with constant particle radiation. They are listed in Professor Thripsted's Flora and Fauna of the Universe as poisonous fungi.

Though they were originally a war-like race, this was inefficient and they turned to commerce, creating the Company. One of the Company's business ventures was moving the Humans of Earth to Mars when Earth became inhabitable. The Humans were nearly taxed to death. When Mars also became uninhabitable, they moved the Humans to Pluto, setting up six artificial suns and taxing them for it. (DW: The Sun Makers)