Aro (ay row): Sex, stimulant, precursor to arotea. Both a hormone and enzyme aro is produced by female orhatea sexual organs that resemble human breasts. In its raw form, aro is a stimulant that is deadly to creatures not adapted to arotea. Mixed with proteins and sugars it acts as any enzyme creating arotea.

Female orhatea can transfer aro with a touch, but will the substance when threatened.

Aro accelerates the growth of arotea, orhatea drones, and Tomo clones. When a creature adapted to arotea injects, or is otherwise exposed to aro they have a moment of euphoria after which they are intensely aware of the substance in their system and can direct it according to their needs, including added strength, sexual stimulation, or—most common—suppressing pain and healing injuries.