Two Tusked Narwhal

An illustration of two narwals, one with two tusks
From The Naturalist's Library by Robert Hamilton, Courtesy of the Biodiversity Heritage Library

The narwhal tusk is actually one of two teeth. In males, the tusk protrudes from the upper, left lip.  While most male narwhals have one tusk, in a few rare cases they can have two, like in the narwhal pictured below.