Xenology (2006), p23

Detail: Unknown 'diamond-organ', in the forehead of the Tau Ethereal. Ridged carapace contains ultradense chemo/hormonal fluids (overpowering scent). Rear ganglia connect to cerebral lobe. Polyp-structures vaguely reminiscent of 'pheromone' glands amongst Terran invertebrates (cf. silk worm). (Spec: Perhaps a pheromonal communication system? The sensitivity of Tau olfactory senses would certainly support a process of airborne chemical 'signifiers'. Perhaps the Ethereal asserts a measure of control over lesser castes? Results are inconclusive, and the purpose of this organ remains unknown.)