Zombieshroom

The Zombieshroom is a boss in Chapter 7 of Mother 3. It blocks the way forward on Tanetane Island after Lucas and company are swept onto the shore by Master Eddy. Its powerful attacks and poison make it able to easily defeat all party members, who at the time will have 1 HP, 0 PP and no items. It can be defeated under the effects of hallucinogenic mushrooms as an Eerie Smile. If it is not encountered before Lucas eats the hallucinogenic mushrooms, it will not be recorded into the Battle Memory.

Battle Memory description
"Recently discovered on Tanetane Island. It's usually rotten, and attracts its food by dancing."