Small, star-like celestial body composed of rock and metal.
A Type-C asteroid crashed into an unpopulated continent of Penthara IV, threatening a nuclear ecological disaster until the Enterprise-D helped dispel its dust cloud. Another asteroid from the Pelloris Field threatened Tessen III with the same type of destruction before it was vaporized by the same starship. Its nitrium alloy core prevented a tractor beam lock, and it was undamaged when hit by photon torpedoes. It was later discovered to be the home of metal parasites.