Possible Clues:

• It's got us in there next to the trunk
• Fleetwood Mac album that went ivory?
• Trumpeter's piece provided material for piano
• To have to carry two such besides the trunk is a beastly lot
• Tooth
• Elephant's or walrus's long pointed tooth
• Mammoth's maimer
• It is found growing next to the trunk
• Sharp projection gets bottom of boat on river
• Narwhal's tooth