Members of this species appear like typical Greys, with short stature, proportionally large heads, hairless grey skin and bulging eyes. Their legs are extremely short, and their arms are long and thin, ending in four-fingered hands, in a similar manner to the Asogians.
They are hermaphrodites, and capable of impregnating other species by transferring eggs to them via mouth contact. Their skin is fireproof, and it's been claimed that they have no bones in their arms, which make them highly flexible. An ooze-like substance known as xenoplasm is expelled from their bodies every seven hours. Some of their inner organs, such as the pancreas, can be accessed by pocket-like flaps on their skin, and safely removed from their bodies, after which the organ will behave as a vicious creature with a mind of its own (indicating that it might be a symbiotic organism, rather than an actual organ). They have described themselves as being made 60% out of electricity and are capable of emitting electrical discharges that can be powerful enough to kill and revive other creatures.
Perhaps most peculiar of all is that members of this species excrete heaps of gold and precious gems, something which is not considered valuable on their planet, naturally. To make it even odder, there seems to be some kind of supernatural curse regarding these excrements, as anyone who possesses them will have bad luck.
Their infamously self-centered behavior is actually a biological trait, as being nice is harmful for their metabolism.
- Among the apparent inconsistencies regarding the biology of this species, one example is the color of their blood. It is possible that they might have multiple circulatory systems and more than one kind of blood.
- In "One Little Word" and "There Will Be Bad Blood", Roger's blood is colored purple.
- in "Irregarding Steve", it is colored yellow during Klaus' fantasy.
- In "Season's Beatings", "Ricky Spanish", "Faking Bad" and "Stan-Dan Deliver", it is colored red, like human blood.
- Another inconsistency regarding this species' biology is the shape and length of their tongues.
- In "A.T. The Abusive Terrestrial", Roger's tongue is long and frog-like.
- In "Great Space Roaster", Roger's tongue is forked and snake-like.
- In "Family Affair" and "A Piñata Named Desire", Roger's tongue is long and pointed.