Secret Door is special 'invisible' door used in a number of traps inside dungeons.
This door isn't placed between two blocks, but instead must be mounted against a 5x2 area of background blocks. Because it's mounted to the background, it also doesn't need to be placed on solid ground.
When placed it makes the background blocks it's placed on appear as foreground blocks. They're indistinguishable visually until the door opens to reveal the background. Because of this unique design, this door can take on the appearance of any pattern of blocks. The horizontal variant of this door is secret trapdoor, which is functionally identical aside from alignment.
|Apex :||There's something odd about this wall...|
|Avian :||There's something odd about this wall...|
|Floran :||Wall is ssstrange...|
|Glitch :||Suspicious. This wall does not appear natural...|
|Human :||There's something odd about this wall...|
|Hylotl :||There is something odd about this wall...|
|Novakid :||Somethin ain't right about this wall...|