A turtle is a variety of reptile. Turtles live both on land and in water. They are characteristic as having a shell into which that can hide their legs, tails and heads.
The Rigellian are a reptillian species that evolved from turtles. (Star Trek: The Motion Picture)
While growing up B'Elanna Torres was made fun of for being half Klingon, she was once called "Miss Turtle Head", by Daniel Byrd, as an insult to her ridges. (VOY: "Juggernaut")
- In Star Trek: The Next Generation, the nickname for Michael Dorn's Klingon prosthetic forehead was "the turtle".