08/29/2026
The Answer: A Mastodon Tusk! A giant tooth with a lot of history!
This fossil fragment comes from a mastodon tusk, an enormous incisor tooth that kept growing throughout the mastodon’s life!
Mastodons used their tusks for all sorts of jobs, including digging, stripping bark from trees, and, especially for males, fighting.
As the tusk grew, it added new layers, a little like the growth rings of a tree. But here’s the surprising part: the oldest layers are on the outside of a mastodon tusk, while the newest layers are added toward the inside.
Mastodons lived in Idaho during the Pliocene Epoch, millions of years ago. Fossils like this one help scientists piece together clues about these incredible animals and the environments they once called home.
Smithsonian Institution/J. Matternes
