In Stephen Baxter’s “Space” (book two in the Manifold Series), the Gaijin are the first aliens to be discovered. When I originally read the book, I assumed that Gaijin was an invented name, but the wonders of E2 have shown me otherwise. They were discovered by Nemoto, who chose to call them simply “foreign” or “alien” in her own language.

And alien is certainly what they are. They are slightly irregular, chunky, metallic dodecahedra, with limbs ending in tools and multi-tools here and there in an asymmetrical manner. When most people see a Gaijin, they assume they are not life, because they fail to meet almost every criteria that we use to identify living things by sight. A typical Gaijin is described here:

A variety of instruments, cameras and other sensors, protruded from the dodecahedron’s skin, and the skin itself was covered with fine bristly wires . Three big robot arms stuck out of that torso, each articulated in two or three places. Two of the arms were resting on the ground, but the third was waving around in the air, fine manipulators at the terminus end working
Despite the Gaijin usually being described as robots, or robotic, they actually evolved naturally on their homeworld, referred to as 0000 (becuase it is the first to be numbered in the Gaijin planet cataloguing system). 0000 is a cannonball world, gigantic iron core and a thin crust (in the context of the book, it seems likely that it was once a larger planet, which has been stripped of outer rock).

The Gaijin have little or no sense of identity, with identity/name/self simply being a list of component parts which are interchangeable. Early in the book, a Gaijin is seen taking itself apart for medical/technical analysis.

The Gaijin use the blue-hoop-teleportation-devices to travel interstellar distances and in Gaijin flower-ships, advanced Bussard ramjet ships, for regular interplanetary travel. They are seen mining helium3 from asteroids with nanotechnology, and have highly efficient solar arrays that beam power to microwave recieving stations on planets.