If you trap the moon in a greenhouse it will grow a creepy membrane around itself. The moon isn't used to the heat it would be exposed to in a greenhouse so that membrane is there to protect it. It's really gross looking though.
You decide to open the greenhouse to check this moon membrane out but when you open the door the smell of big macs (まく) hits you in the face. Eww. Why does this membrane smell like a big mac... or does that mean big macs smell like a festering moon?