They are dark blue with red lips and have a helmet on their heads. Inside their helmets are their brains. They also have orange hair sticking out of the sides of their heads. They have look similar to Lord Royal Highness.
They seem, judging from their origin story of their bubble, to come from another planet.
Atlanteans mostly work in the Royal Castle, as those are most of the known jobs. Known occupations are:
Atlantean minters (shut down)
The Atlanteans are seen as males in the episode. However, in the consoles versions of the video game adaptation, one can hear a female voice.