Excalbia
Excalbia was an inhabited planet located in an unidentified solar system. This was the homeworld for the Excalbians, a species of intelligent and advanced carbon cycle life forms.

The planet had a poisonous atmosphere and a surface that consisted mostly of molten lava. The planet was located hundreds of light years from Earth.

In 2269, the  was sent to Excalbia by Starfleet to confirm several "old space legends" about the planet, which suggested that the planet was home to intelligent life. Orbital scans of Excalbia revealed several scientifically anomalous readings, with indications of artificial  being generated in factor seven quantities, indicating the presence of a considerable civilization.

As the Enterprise prepared to warp out of orbit, the ship was subjected to an incredibly swift deep probe from the planet. Moments later, the ship was contacted by the  Abraham Lincoln, who eventually convinced Captain Kirk and Spock to beam down to Excalbia's surface, of which, a Earth-like area of approximately 1,000 square kilometers was created. On the planet's surface, Spock and Kirk were subjected to an Excalbian experiment on the nature of good and evil conducted by Yarnek with Kirk and Spock's unwilling participation. Yarnek recreated several historical figures thought to embody the concepts of good and evil, and pitted them in combat against each other before the Enterprise crew was allowed to depart. ()

In 2328, this was home to the Excalbia Tourist Resort. (, okudagram)

A diorama of Excalbia was created by noted  Kerner Hauze aboard his ship. Following his death in 2381, the display was severely damaged by the ship's own automated defenses as it pursued the  away team that was aboard cataloguing the collection. ()

Appendices

Background information 
According to Star Trek: Star Charts (p. 23), Excalbia was classified as an E class planet.

Apocrypha 
According to The Worlds of the Federation, Excalbia is the first planet in its system.

External links 
  
 

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ja:エクスカルビア
Planets
Homeworlds