Composed of rock and crystal
In 58 BBY, while still a Padawan who had not built his own lightsaber, Mace Windu was sent to Hurikane to negotiate with these beings and possibly obtain special lightsaber crystals from them. The mission did not start out well, resulting in Windu being chased by several members of the species.
When one of his pursuers fell into a canyon, the young Padawan turned back to heal the being's broken body by using the Force. In gratitude, Mace received some of the crystals from the being's body—the very Hurrikane crystals he sought.