Sea cow used for Iban hilts

[Tim Simmons]

Bone density might be the answer here. Dugong are not deep diving sea mammals so thier bones are more dense than whales. As they live in water they have less dense bones for buoyancy. Land mammals have heavier dense bones certainly bones big enough for sword handles will be hard and dense. So if the bone is light and spongiform it may well be Dugong. Some interesting stuff on bone to follow when an item finishes on ebay.