Shroob is a Spice which they're alien!..before the modern living of mario and gangs...These shroobs needs to find a home to live there they choose Princess peach's classic castle!...They attack there!..and after the game...Bowser and his minion Freezed those shroobs and princess shroob in a freeze room!..however,they didn't appear in MBAV...But it's confimred some shroobs which they'd froozen by koopas along with princess shroob they will escape!....
It was one of the Badass's Mushroom kingdom for Past!
Trivia[]
1-They look like Posion Mushroom