The tusk represents human strength, and the ancestral connection with the animal's spirits, those who the humans, in the cradle of civilization, had to face to survive. The tusk of the defeated animal was worn, so its spirit was now at the service of the man. Carrying it in the neck symbolizes the ability to overcome adversaries, and the men's power to prevail in any situation. It's believed that it makes the inner strength arise, that connects us with elder powers and makes us invincible. It also increases the sexual appeal.
The bear is a symbol of power and mutual respect.
The wolf is a symbol of power and courage in some cultures.
Shark Tooth: Used as an amulet since prehistory. The carrier would acquire the power, ferocity and strength of the shark.
Eagle. Power and protection symbol. Many native American tribes considered it a messenger from the gods before it became the symbol of the USA it is today, appearing in the American seal or in American coins. It also was a symbol of ancient European empires.
The Bat, in the western culture, is usually seen as a symbol of the night and the forbidden nature. In the Mesoamerican mythology, the bat is part of the mysterious world related to warriors.