Turtle shells evolved over the course of 300 million years, but self-defense wasn't the initial driver, researchers think.

Leatherback turtles are named for their shell, which is leather-like rather than hard, like other turtles. They are the largest sea turtle species and also one of the most migratory, crossing both the ...

This file includes stroke(), which converts a path into a geometric object, like drawing with a pen. It even works on three-dimensional paths. You can make a dashed line or add arrow heads. The turtle ...