From Creatures Wikia
The Mask Norns were created by Jewels. All the three original Creatures 3 breeds Bengal Norns, Bruin Norns and Civet Norns got a colourful look, resulting in three new breeds, the Bengal Mask, the Bruin Mask and the Civet Mask Norns. The colours of their sprites change with every move they make. Jewels dedicated the Mask Norns to her sister Jennifer and her unborn baby, who were both killed in a car accident caused by a drunk driver.
The Mask Norns used to occupy Norn breed slots M, N and O. As later the released Astro Norns , Hardman Norns and Harlequin Norns occupied the same breed slots, the sprites got converted to Geat breed slots.