Pseudoor

The Pseudoor is an enemy in Mother 3. It is located in a long hallway in Osohe Castle, and acts as a trap. If Duster's party touches it, it will attack. The real door is the one on the far right at the end of the hallway. The Pseudoor is very susceptible to crying. If the player successfully runs from battle, the Pseudoor's overworld sprite will change.

Battle Memory description
"No matter how long it takes, this door anxiously waits for someone to open it. It's been waiting for years now."