Skulls are boiled and treated with enzymes or enzyme substrates to produce a clean finish without degrading the bone No artificial sealants have been used as they can alter the color and texture of the bone Bison skulls are roughly 19-21 inches long from top of head to bottom of jaw, about 10 1/2 inches wide at the eye sockets and 8-9 inches deep Horn spread from tip to tip is 20-26 inches depending on the curvature of the horns.