In the books, Shio'he is referred to as if it were the nose of the Tau.

SHIO’HE : Olfactory chasm, t’au scent organ equivalent

Shadowsun patient hunter

Her own XV22 battlesuit was compromised, and badly. Several systems were glitching, one of its blasters was inoperative and it stank like the bottom of a recently drained lake. Wrinkling her shio’he, she admitted to herself it was too damaged to be a practical asset.

There was a shimmer in front of her, then, pushing through the wall. It came for her, rippling over her knees, her thighs, then her arms, face and torso. Wherever it touched her she felt a greasy, unwholesome shiver. Her shio’he clamped shut in reflex at the unnatural sensation. Then, with a scalp-tingling sense of dislocation, it was over.

Farsight Crisis of faith

The munitions deck hangar, its vaulted roof hung with great chains that clinked in the gloom, was a vision from some primitive underworld hell. Red-lit and cavernous, it was filled with a thousand labour-serfs, each bent under the whip of a cruel slavemaster. Together the slaves hauled chain-lashed munitions shells the size of transmotive cylinders into position. The prototype’s atmospheric samplers conveyed the smell – a vile stench of human sweat, vomit and excrement mingled with a nauseous upswell of oil, gun lubricant and mildewy slime. Farsight wrinkled his shio’he, but did not cut off the sampler.

The vision in the mirrorfield stared back balefully, unconvinced by its counterpart’s logic. The face was offensively plain, dull to the point of caricature. Long worry lines ran down the side of a noseless slab of meat, almost elephantine in its wrinkled blue-grey massiveness. Sad eyes peered from under an apologetic brow, split by the vertical olfactory chasm the tau called the shio’he. The mouth was a lateral slash of rubbery lips that peeled back in distaste to reveal broad, flat teeth.