Across the Galaxy, the Angelics had terraformed thousands upon thousands of worlds in their 500 million year reign.  Most of these worlds were worked over so thoroughly that, defying terraforming convention, their transformation not only remained intact on a scale of millions of years, but often it literally "kick started" a planet into a self-sustaining cycle much as any true Gaian world experiences.  Indeed, worlds orbiting lesser massed stars, which have survived until the modern era, would are nearly indistinguishable from planets that had evolved natural biospheres.  In these many cases, the life forms present, be they natural or planted by the Angelics, often evolved to the point where intelligence arose.  In at least one case, this resulting intelligence lead to the true successors of the Angelics, and the first galactic civilization since that ancient race had vanished.

The Dunwalli evolved and technologically matured at a pace that one could describe as average.  Within a few thousand years of learning agriculture, they began to migrate outward into their solar system, and a few hundred years after that they began to populate neighboring star systems.  In time they would be destined to colonize half of the Galaxy, but even before they achieved this they began to practice an art that would define them to all those who knew of them.  In the Local Neighborhood, at least one example is also known, and the scale of the engineering needed to create such a thing is amazing indeed.

Megastructures are constructions that are literally worlds in their own right.  The least examples are habitats such as Bernal Spheres or Stanford Torii.  But there have been known theoretical major examples known for some time.  Among these are orbital rings, artificial rings that encircle a star, their inner surfaces engineered to be habitable.  While in reality such rings are inherently unstable after only a few thousand years, and would begin to drift off-center of the star and eventually impact it, smaller versions in orbit of a star are quite possible.  And it was just such a type of construction that the Dunwalli began to construct, and began to excel at.

The Dunwalli arose to their earliest civilization 2.6 billion years ago, and for 400 million years they managed to spread across the Galaxy.  Like their Angelic antecedents, they learned to terraform worlds and to genetically adapt themselves and other species to various environments and tasks.  But it was the construction of ring habitats that became their specialty.  Averaging 2 thousand kilometers in diameter, these Dunwalli rings were constructed from asteroids native to a chosen system, asteroids that were literally broken down into raw materials, and reassembled into the rings, their materials transformed into a composite of diamondoid and carbon buckyfiber.  Set into a rotation strong enough to produce a centrifugal gravity of 0.8 G's, the inner surface of the rings are replicas of the original Dunwalli homeworld, at least as far as the environment goes.  The land to water-ration is varied from ring to ring, but the climatic conditions are always the same.  For the span of their tenure in the Galaxy, the Dunwalli lived in these rings, carefully tending the megastructures, repairing when necessary, adjusting upon occasion.  But as time wore on, the Dunwalli became less and less numerous, until finally there was a period when no Dunwalli seemed to remain anywhere in the Galaxy.  Like the Angelics, the Dunwalli had faded away, leaving behind reminders of themselves scattered across half of the Milky Way.

For the most part, the Dunwalli rings eventually succumbed to the irresistible forces of the aging stars that they orbited.  Destruction was inevitable as these comparatively fragile structures had to contend with brightening and expanding stars.  Only those that had been built about late K-type stars or red dwarfs seem to have survived.  Of these, many had their ecologies fail due to environmental breakdown.  But others, so very few others, thrived.  Their ecologies continued to adapt and evolve.  And at least in one case, an intelligent species arose, and they moved out into the Galaxy, the latest inheritors of a Galactic legacy that began with the long vanished Angelics.

Updates

December 2, 2006

• Added a sketch of the Dunwalli, by Neal Aaron.

March 25, 2006:  Added some graphics for the Dunwalli archaeological artifacts.

March 22, 2006:  Some minor updates to the text, primarily dealing with information on Dunwall.

February 18, 2006:  Established this page and its data.

Classification:  Dunwalli sapiens sapiens
Biochemistry:  Carbon-based, as evidenced by extant biosphere on the ring Dunwall
Morphology:  Endo- and exoskeletal elements on a large serpentine frame, with three manipulator limbs and six pairs of locomotive appendages along the sides of the body.
Environment:  A gravity of 0.8 preferred, with a somewhat swampy terrain punctuated by dry hillocks.  Possibly a biological analogy to crocodilians, however loosely based.
Reproduction:  Sexual reproduction between two different sexes.
Intelligence:  High technical civilization capable of massive terrestrial constructions, terraforming, megastructure construction, etc.  Interstellar capability over 400 million years, leading to a heavy colonization of at least half of the Milky Way.

The evolutionary ancestors of the Dunwalli seem to have filled an ecological role similar to that of Earthly crocodilians.  However, these creatures, swamp-bound though they may have been, were the top of their food chain and immersed within a rich biosphere.  Food was plentiful, and they had the larger brains often afforded to predators.  But what was more, they had rather dexterous limbs, three of them in fact, which allowed them to manipulate their surroundings.  Over several million years, all of this allowed the pre-Dunwalli to evolve into a sapient, curious species.

Moving on twelve legs, covered in a tough, scaly exoskeleton, the Dunwalli appeared to be more animalistic than they did intelligent.  However, as they learned to manipulate their surroundings, their favored dry hillocks, protruding from the surrounding swamps, became covered with wood constructions.  In time they began to move away from the swamps, and walled cities arose, though to the Human eye they might have appeared more as fortified, brick-sided termite mounds.  But in time the Dunwalli moved off of their world and into space, and they began their 400 million year career of creating some of the most awe-inspiring megastructures imaginable.

The primary artifact of the Dunwalli to be found in the Local Neighborhood is, of course, the ring of Dunwall.  This artificial structure orbits the red dwarf Gliese 643, a far member of a rather complex group of red dwarfs.  Dunwall is in a stable orbit, and possesses a nearly equal division of land and water, along with an atmo

The Trans-System Clarke Habitat, so named because of its orbit that reaches fully half way to the Gliese 643 A-BaBb System, and its resemblance to a fictional habitat described by the 20th Century speculative author, Arthur C. Clarke, is one example.  The TSCH (often pronounced "tish" by Dunwalli experts) was discovered when a faint trail of dust and gas, produced by the now ceased escape of atmosphere from the object, was tracked to a position far outside of the system.

The habitat itself is nearly 12 kilometers in length, is cylindrical in basic shape, and rotates at a rate which provides the inner surface a gravity of 0.8 that of Earth. The habitat is covered with various instruments and panels, all of which have been highly eroded by over 2 billion years worth of erosion.  The outer shell of the habitat, however, is a thickened layer of carbonaceous rock, which bears the scars of many meteorite impacts.  Indeed, a very quick look from a distance gives the impression of a cylindrical asteroid.  However, there is a large structure protruding from what has become considered the aft end of the cylinder, reaching out a full kilometer.  Made up of what could be described as shunts and supports, even load-bearing members, the very end of this structure is quite twisted, indicating that possibly there was once more to it, and that some large module has long since been ripped away from the overall construction.  Many believe it to have been a drive of some sort, and the theory that this was an example of Dunwalli interstellar craft from some period of their history is a popular explanation.

The interior of the habitat is airless, with a temperature hovering close to absolute zero.  But there is a thick layer of frozen soil within, as well as some very carefully sculpted "mountains" and other land forms.  There are even meandering channels that once likely held rivers, and basins which may have once been lakes.  However, the lack of pressure has lead to the loss of all internal moisture.  The long trail of gas behind the TSCH points to an extended period of atmospheric loss, and certainly all internal moisture that hadn't been trapped and frozen would have sublimated and escaped the craft along with the air as the atmospheric pressure lowered.

Biological remains have been found, but the cold has damaged any cellular remains beyond the ability to properly investigate.  However, it can be determined that, at one time, the habitat was quite lush with plant growth, as well as a fair number of small organisms.  Interestingly, though, there seems to be a complete lack of bacterial remains, indicating that, even when inhabitable, the TSCH was fairly sterile.

Located in a close solar orbit to Gliese 643 is the third and final known Dunwalli artifact, and it is perhaps the most enigmatic.  This artifact looks as if someone has sent a great needle tumbling away into space.  The object is 3.7 kilometers in length, and only 700.3 meters in width.  It is very dense, highly reflective, and may represent some piece of pure Dunwalli technology.  Its purpose, though, is completely unknown.  With absolutely no interior spaces, some have speculated it was part of, or even the entire drive portion of a Dunwalli interstellar vehicle, possibly the missing section of the TSCH.  A few have proposed that it was nothing more than an expression of abstract art.

The truth is, no one knows what the Spindle does, or did.  Soundings have shown it to be filled with what could be machinery of some sort, but there has never been any indication of any power emissions from it.