Class A geothermal planet

Class A planets are usually in the very early stages of development and are likely to evolve into other classes. No life-forms have ever been discovered on these planets. In 2267, the USS Enterprise encountered a rogue Class A planet named Gothos. It was discovered that Gothos was created by Trelane, a member of the Q Continuum, as a sort of playroom to test the crew of the Enterprise. (TOS episode: "The Squire of Gothos", and reference book: Star Trek: Star Charts).