Imprint
Alternate timeline
(covers information from an alternate timeline)
A cast of Alexander's ridges
An imprint was the impression of the surface of an object pressed into a pliable material.
In an alternate 2370, Alexander Rozhenko made a clay mold of his cranial ridge to give to his father, Worf, for his birthday. Deanna Troi passed it on after the boy left to visit his grandparents. Upon opening it, Worf smiled, explaining to Troi, that they were "[t]he ridges of a warrior." (TNG: "Parallels")
According to the script, which verified the material as clay, this was "the Klingon equivalent of a child's hand-print."