Item from Hyperion by Dan Simmons
Templar energy creatures that make treeships spaceworthy — living containment fields that wrap kilometer-long trees in force that lets them sail between stars.
Ergs are the Templar Brotherhood's most precious resource — living energy creatures that generate containment fields capable of making their kilometer-long treeships spaceworthy. Without ergs, a treeship is just an enormous tree. With one, it's a starship. Het Masteen brought an erg in a Mobius Cube to the pilgrimage — his mission was connected to using the erg with the Tree of Pain, though his untold tale means the details remain mysterious. The Templars' relationship with ergs reflects their broader philosophy: technology as symbiosis with nature, not domination of it.
Energy beings — not visible in the traditional sense but perceptible as fields of force that wrap around the massive Templar treeships. They provide the containment fields that make a living tree spaceworthy.
Also known as: Erg, Energy Creature