The horn (material) is mountain sheep.

Haida trading canoes returning from the Nass brought with them as part of their cargo the horns of mountain sheep, from which they made spoons and bowls. The species native to the northern coastal mountains is the Dall sheep, with amber horns somewhat less massive than those of the bighorn sheep. Mountain rams' horns form large, tapered spirals of very tough resilient material which can be carved with woodworking tools and has the quality of becoming soft and flexible when soaked and heated. (Holm, Spirit and Ancestor, 1987)