ELEPHANT: The tusks are round and composed of cementum and dentine, enamel is found only on the tip where it wears off at an early age. The outside surface has wavy longitudinal bands. In cross-section it has a tree ring pattern with a central black nerve dot and lines that cross to form a diamond pattern called "cross hatching".

MAMMOTH:
Similar to elephant, except that the "cross hatching" is in a tighter pattern that, when measured, is below 100  degrees. Elephant measures above 100 degrees. Mammoth ivory often has a blue-gray or brown coloration on the outside of the tusk from minerals in the soil often referred to as the "bark".

WALRUS:
These tusks are slightly curved and oval in shape, with an exterior composed of cementum. The interior has a primary dentine with a marbled looking secondary dentine that is diagnostic to walrus. Fossil walrus like mammoth will be colored.

HIPPO:
Three kinds of teeth are used--the incisors, and the upper and lower canines. The incisors are round and the canines are triangular. They have exterior enamel, a transition ring between the dentine and cementum and a nerve root that is arched (called TIZ). The grain is fine and follows the shape of the tooth. Radial cracks are often seen.

SPERM WHALE:
The teeth, all from the lower jaw, are conical shaped and composed of cementum and dentine. Only a small amount of enamel is on the tip and often is worn off in cross-section

NARWHAL CROSS SECTION
A gross spiral morphology, hollow interior to the tip, transition ring, radial cracks, and lines that follow the shape of the tusk.