Marty is a cow. He found some archeological article about Viking masks of a cow and a sheep. Neither Keith nor I had ever heard of it. What he found said the masks were fastened to close-fitting hoods, and he had this hood from when he was younger. It's felt, and he painted the knotwork on with Holly's advice and assistance. It's jowls, a nose and eyebrows.
What Marty found is halfway down this page: vikinganswerlady.com/masks