Depictions of kitsune or their possessed victims may feature round or onion @-@ shaped white balls known as hoshi no tama ( ほしのたま , star balls ) . Tales describe these as glowing with kitsunebi . Some stories identify them as magical jewels or pearls . When not in human form or possessing a human , a kitsune keep the ball in its mouth or carry it on its tail . Jewels are a common symbol of Inari , and representations of sacred Inari foxes without them are rare .