From Starbounder - Starbound Wiki
Ancient Door is an object unobtainable by players through normal means. This item's information is present in the game files, but not intended by developers to be in players' possession.
Ancient Door is a door type object.
|Apex :||A door made of an ancient stone.|
|Avian :||A sturdy door of ancient origin.|
|Floran :||Looksss like an ancient door.|
|Glitch :||Guarded. It would not be surprising if this ancient door failed to open.|
|Human :||I bet these runes say 'open' and 'close'.|
|Hylotl :||This door is a relic of a time long past.|
|Novakid :||This 'ol door is a relic.|