From Starbounder - Starbound Wiki
Rusty Block 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.
|Floran :||Russsty metal blockss.|
|Glitch :||Horrified. This rusty discarded metal is weathered and worn.|
|Novakid :||This here metal looks mighty rusty.|