Tusk material
According to Gettlemen, as much of 70 percent of the... [DOC] [TLE] ivory | Britannica.com [PAR] Variety of dentin of which the tusk of the elephant is composed and which is ... 
Ivory is a very durable material that is not easily damaged or destroyed; it will not
... [DOC] [TLE] Mysteries of evolution: the narwhal's tusk, or rather, tooth  Why ... [PAR] Apr 22, 2012 ... Because, with the exception of its tusk, the narwhal has no teeth.